bbradford wrote:
I use the d750 now and love it. My thinking is better resolution and some features like focus stacking along with longer shutter life. Maybe I just have gas. Lol
There are ways to accomplish focus stacking with a D750.
And, with stationary subjects you can "amplify" the resolution of any camera by using a multi-shot technique and stitching the images together (which obviously doesn't work well with moving subjects).
Besides.... what do you do with your images? Do you make large prints? You'd have to make prints 16x24" or bigger before you'd start to see much difference between a 24MP camera and a 45MP camera. Don't rely upon viewing your images on a computer monitor... especially not at ridiculously high magnifications. On most monitors anything more than 33% is just silly when it comes to evaluating resolution, sharpness, noise, etc. Yes, retouching and some other things can be done at high magnifications. But viewing 24MP image "at 100%" is like making a 40" by 60" (five foot wide!) print, then viewing it from 18 to 20" away! Or do you find yourself cropping a lot? That's another way to cause worries about resolution. But the solution may not be the camera. Maybe your money would be better spent on a longer telephoto lens so that you can "fill the viewfinder" with your subject and crop less or not crop at all.
As to shutter count... that's always just an estimated life. It's what the engineers who designed the camera think that the materials and construction can be expected to do over time and with use. Nikon rates the D750 to do 150,000 clicks, while Canon rates the R5 to do 500,000.
This site shows "real world" that over half of D750 reported survived over 500,000 clicks. However, it needs to be noted this isn't a very scientific survey. It's purely voluntary, relies upon people giving accurate info without any way of confirming it, and the numbers are too small to be considered a very accurate survey (there are only 27 total D750 reported with 500,000 or more clicks). Still, it's all we've got:
https://www.olegkikin.com/shutterlife/nikon_d750.htmMany (most?) cameras exceed their manufacturer's click count ratings. Often, though not always. (Canon 40D for example, fell quite a bit short of its 100,000 rating. But the 30D that preceded it and the 50D that followed both easily met the same predicted life span. I doubt anyone other than Canon knows why.)
The R5 is too new and not in enough hands for there to be similar durability reporting. Check back in 5 or 6 years. D750 is close to 8 years old now, was intro'd in mid-2014. The R5 is only approaching 2 years, intro'd in mid-2020. Even so, with D750 selling in the $2000 range and the R5 selling for virtually double that, there are likely to be far fewer R5 in circulation than there are D750.
Besides, a camera's shutter isn't the only part that wears out and not all "clicks" are created equal. It's like car mileage... a rather crude method of tracking usage. A car that's only ever used around town for short trips will have a lot more wear and tear than a car that racks up higher miles on far fewer long road trips at highways speeds. It's similar with cameras. Since many cameras are now able to shoot both video and stills, the wear on many components can differ wildly depending upon their primary use. A camera that's used to shoot a 15 minute video will have a single click on its shutter count. But that same 15 minutes is equivalent to 225,000 actuations at 1/250 shutter speed. A camera used a lot for video may have very low shutter count, but a whole lot of "time" on all the electronic components. Conversely, a camera only ever used to take stills may have a very high shutter count, but very little total time on those same electronic components.
All this IS NOT to say there aren't some definite advantages to mirrorless and the Canon R5 is one of the better models out there right now. But there are also a lot of positives about DSLRs and the D750 is one of the best examples of those.