Other than the early adopter issues Brian mentioned there is no downside to the 722. There are some nitpicking issues: menu operation, metering, meter LEDs too bright on lowest setting, XLR spacing won't permit two RA-XLRs. Just stupid little shit that I mention only because if those are the kinds of things people complain about, it's a damn solid piece of gear. It's crotchable and if that is an important attribute for you, there is nothing else that can beat the 722 for size, sound, and price at 24/96 right now.
With regards to the MK4/41>722, you are going to get a warm tape. I often prefer neumanns over schoeps but I always like the 41s because of what they can do in a bad room. So I'm not bashing when I say that to me, the few schoeps->722 I've heard are heavy sounding. The 722 itself seems warm compared to the V3 and I think it's a good mate for the neumann mics. However, I was ready to unload my V3 until this evening when I got a chance to hear the KM143->V3 24/48 source compared to my KM140->722 24/96 of the Charlottesville mule. I like my recording but I think the V3 source is better. I've got enough time with the 40s/43s and V3 that I can account for the different capsules and room position. There is something about the V3 that I like a bit better. So for me, I am back to thinking that I'll run the V3 ahead of the 722 for taping situations like festivals where I have plenty of room for gear and no hassles with carrying SLA batteries for the V3. For stealth or any situation where I want to be low profile, the 722 all by itself will still make a recording that competes with anything else. But that's with the neumanns. I think that if I were running schoeps, I'd favor a V3.
If you get the 722 only, I think you'll be happy. If you do get a V3 and then buy a recorder, you can't get anything else that is small and can double as a 24/96 stealth deck when needed as the 722.