I pre-ordered the 800E yesterday.
I have wanted to go higher quality since my 1DsII days. But I had to quit serious work due to disability and closed my studio 5 years ago, so I could not justify a MFDB. It hurts just to take photos of equipment I am selling for eBay!

(4 bad disks in my neck, 3 bad disks in my lower back, tear in my shoulder ...)
I was waiting for the 5D3. I have a ton of great Canon glass, but I will do the switch if Canon doesn't announce the 5D3 before the 800 ships.
I used to print at 180 dpi at 18x27 non-rezzed on the 1DsII. I was happy with that for 75% of my work. For anything larger I have been using 4x5 film and scanning.
The 800 can print at 27"x40" at around 200-210 dpi. I can live with that as a maximum print size if quality holds up as expected. I hope the absence of the AA helps me tweak a little extra quality out of the system. 90% of what I shoot is ISO 100.
My plan is to find a younger photographer to collaborate with. I have a full Broncolor studio kit and 30 years of experience. But I can't do the physical work any more.
I had been looking at 22MP MF cameras and/or backs. But it is nice to have the 35mm contained form factor and not have to struggle with some of the complexities of MF. I am selling off all of my 4x5 (6 camera kits) and MF film cameras now. (Mostly because I can't handle it physically any more, not because of the 800E.)
I still have 2 Epson 24" and a 44" printer. I like to proof at 24x36, I love big prints.
Still hoping Canon replies soon to save me from swapping out systems. The 5DII is still a pretty decent camera after 3 years, so I expect the 800E or equivalent will suffice for most general purposes for 5 years.
Good times! I am very happy.
Michael