This is all fantastic real world experience. Exactly what i was hoping for. I really appreciate everyones input!!

Just to confirm, the RP would have improved autofocus even using an adapter and EF lenses? I thought this was only the case using RF lenses

Thanks for the tip. I've also been looking at referbs from Canon.

Great point. Makes total sense.

I don't have any experience with mirrorless, so opinions are very welcome. And I have a fairly solid compliment of EF lenses (70-200 2.8, 85 1.8, 50 1.8, 17-50 2.8, 11-18 4.5, and 100-600 5.0).

"From the specs it appears the 6D Mark II is no more sensitive than the 80D"

Great refs. Thanks. I think you may have looked at the ISO comparison for video, which is about the same for all 3. The ISO sensitivity for image capture looks to be about 4x higher for the 2 full frame bodies, unless I'm reading it wrong. Both full frame and mirrorless is new to me, so I could easily be mistaken.

That's what I'm leaning toward. The 6d Mark II seems to consistently get great reviews. Thanks for the input!

I'm currently using a Canon EOS 80d (which has been great for my needs) but have been thinking about moving to a full frame. I mostly shoot portrait, some sports, and am currently getting into cave photography. My rationale for full frame is mostly to take full advantage of the L glass that I have and to increase low-light capabilities (my #1 motivator). My two primary constraints are price (trying to stay around or under $1k for a body so I can stay married) and size (anything larger than the 80d will be challenging based on how I transport my equipment, especially when caving, which knocks out the 5d's).

I've been looking at both the 6d mark II and the mirrorless RP as a replacement for my 80d. I know all 3 of these have very similar technology, but both full frames would give me a significant bump in IOS. Both choices would compromise burst speed and max shutter speed, but I don't think either of these would be a limiting factor. I am a bit concerned about using EF lens on an RP body, but I think this is only because I don't have any experience with mirrorless.

Any thoughts, experience, or opinions would be greatly appreciated, especially since this is close to a lateral move.

You have perfect timing… I was just out caving this weekend. IMHO I’d be less concerned about lenses and more concerned about lighting. I typically shot with an 11-16 lens on a APS body and rarely feel the need to switch lenses underground (except for macro). The real beauty of caves is that you have full control of your light (although in this case there is lighting along the path). I rely on 2 basic strategies. Either a tripod for long exposures (allows for low light or multiple pops with a single handheld flash) or multiple radio controlled flashes (my preference). 3-5 flashes with a radio trigger (I use Godox) allows for a ton of flexibility (I would avoid on-camera flash since the results will be extremely flat). Considering this is a commercial cave, I would opt for a tripod and 1-2 off-camera flashes). A good starting point is f8-11, 1/100 shutter speed, ISO 200, with flashes at 1/16-full power (plastic diffusers and hot shoe bases can help a lot). People/models provide scale, a good focal point to draw your eye, and color (to break up some of the earth tones). Hope that helps a bit. Have fun, stay safe, and please post some of your results.

What camera does your Light & Motion housing fit?

I've tried the G9X Mark II and was very disappointed. IMHO nowhere near the image quality of the G16 and not at all intuitive from a controls standpoint. Shutter seemed sluggish, and low light performance was poor. Also no hot shoe or viewfinder. I keep looking for a suitable replacement, but so far the G16 is tops in my book.

Absolutely love my G16 (I actually have 2). It's my go-to travel camera (always in my backpack) and also my primary underwater camera (I use a Fantasea case which provides full control of all camera functions... this is also why I have a back-up body). Provides great images and full manual control. I've tried a number of other "high end" point and shoot cameras and have yet to find anything that compares to the G16. Many of the newer models have moved to touch screen control which I find extremely cumbersome. I'm old school... I like knobs! I've found the G16 to have well laid out controls that are very intuitive. If you shoot with a DSLR (I shoot with a Canon d80), the G16 controls should make perfect sense. I especially like the adjustment dial in the front just below the shutter button which allows for rapid adjustments and it also has a hot shoe which I find is missing on many smaller cameras (critical if you use off-camera flash or do macro work). It's not a DSLR, nor is it a mini point and shoot, but for someone serious about photography, I think it's an amazing bridge camera. (As with most cameras that have a retractible lens, this is definitely a weak point in the design. I had to replace my lens assembly about 2 years ago, but Canon did a great job for under $200)

I have 2 g16's that I've been using for years (mostly for underwater work). Fantastic little cameras IMHO. I had a similar issue with one where the lens cover leaves would get stuck, so I sent it back to canon for repair. Their standard repair rate is $180 on these cameras, and I received a similar invoice saying "repaired and tested." When I followed up to get more detail (because I would have been pissed if all they did was blow out dust from the lens cover), their detailed report showed that they had replaced the entire lens assembly, installed new battery terminals, and tested / recalibrated the entire system. That was over a year ago and it's been shooting like a new camera since. Yes it's expensive, but they do it right. It also took less than a week to get it back. Your G12 is a much earlier generation, so I'd ask yourself how much you really like the camera. You could upgrade to a newer model (used of course) for a similar cost of repair. Hope that helps.

Thanks for the thoughts. I always rely on reviews, specs and user comments as a starting point, but am often disappointed with how they translate into practice. I think it's probably due to the "class" of cameras that are being compared. As you pointed out, the SX series is good for what it is, but the G series is built differently (as an example, there were numerous user comments re how great the SX620 is in low light... but it didn't even come close to meeting my expectations... which I know is completely unfair since I'm comparing it to a G16). That's why I was really hoping for some UHH input. I've looked at Sony & Panasonic, but the Canon seems to be the most reasonably priced (and I'm a long time Canon user... so a bit skewed in that direction). From what I can tell, the G9x II seems to have similar performance characteristics to the G16 but with a more "consumer oriented" form factor and interface. Thanks again for the input and I'll give Sony & Panasonic another look!

Lately I've been loaning out my G16 to take "snapshots" for some of our work events. Always takes great images, but the camera is getting beat up, so I'm looking for an alternative camera for company use. (I also hate loaning out any of my personal equipment). I've tried several of the Canon SX series cameras, but have been unhappy with their low light performance (much of our work is indoors without a flash). Right now I'm considering the G9x Mark II (not the original G9 which had some issues) and would love to hear if anyone has had experience with this camera. And please remember, this would be used primarily for "snapshots" in relatively low light environments (classrooms) and not intended as an alternative to a dslr. Budget is also an issue (a refurbished G9x II with a 1-yr warranty runs ~$350). Thanks in advance for your thoughts.