And remember, Burkphoto is right that there is another source of 4/3rds cameras. Even if you buy an Olympus today, and see a future Panasonic body in the future you want, you lose no lenses by buying the Panasonic body. And vice versa. I will still recomend the Olympus design over the Panasonic design unless you do a fair amount of video. Then the Panasonic design may hold an advantage for you. And there are some UHHs that actually have both Olympus and Panasonic bodies with Olympus and Panasonic lenses. How can the 4/3rds system get better than that.

I cannot recommend the Mk11 more highly - blindingly fast accurate autofocus, world class in-camera image stabilisation - I won't bang on as I'm sure you've checked

as I'm getting on (in age) I sold my D1 and half a ton of lenses about 5 years ago and bought an an Olympus EM-5 with a couple of cheap lenses. Moved to an EM-1 after two years, with better lenses and finally a couple of months ago took the leap to an EM-1 Mk 11. You are really spoilt for choice with lenses and can use older four thirds lenses with a simple adapter and full functionality. After a lot of trial and error I have settled on three lenses for my travels.

12 - 40 2.8 pro (olympus) around $700 new
40 - 150 2.8 pro with 1.4 teleconverter (Olympus) around $1400 new
25 1.4 Summilux Leica around $600 new

all of three which together cost less and weigh not much more than one Canon EF 70-200MM f/2.8

All of my three lenses highly rated on DXO and I am very pleased with results.

The Olympus menus and buttons take a lot of getting used to - after 5 years I still find things I didn't know existed.

Performance is brilliant, not so hot in very low light situations but that is the tradeoff for losing a lot of weight. I won't go into all the benefits - you can check it out on any photo mag page.

I couldn't be happier and attach a couple of pics I took on a recent trip to Uganda with the Mk11 and two 2.8 pro lenses and one pic of a dragon taken wth the lttle Leica 1.4

I will throw in my 2 cents as a long time Olympus shooter and owner of both the EM1 and the EM1 II.
The mark II is a big improvement over the EM1 in several ways - better noise control, quieter shutter, and has 2 SD card slots.
In either case, pay for the good glass. I have the F2.8 12-40MM, the 2.8 40-150MM, the F2.8 7-14MM, and the F1.5 45MM lenses and love them all.

Need shallow depth of field? The faster glass helps, but with the crop factor, F2.8 is not the same on the Olympus as on a full frame (not as shallow).
Solution? Use a longer lens and get further back. You can get great portraits with the 12-40, better with the 45, and really control the DOF with the 40 to 150.

Shooting lots of landscapes? The DOF challenge is in your favor here since you can use a larger aperture and higher shutter speed (don't ask me to get technical,
but think of how much more depth of field you get with a small sensor phone camera compared to a full frame).

The lightness is definitely good, but good glass weighs more no matter what, so if you have been shooting a Rebel kit with kit lens and you move up to what I have, you might not notice
the lighter factor. However, comparing the EM1 II to a higher end DSLR with quality glass, you will not be disappointed.

You can check out some shots I have made at www.RonD-Photography.SmugMug.com - all photos were shot with Olympus cameras (E330, E620, PM1, EM1, EM10, and EM1 II).
On my wall I have 24"X30" (approx) photos from each camera and am happy with all of them.