I was a fairly early adopter of the 722, not the first here for sure, and there were no other options available for an all in one solution. I was previously hauling 30-40lbs. to a show. Now I am @ ~5lbs which will get me 12hrs. of nonstop recording, throw in an extra pound and i can get around 30hours. I had become used to the HD recording since I had a JB3 and wasn't looking forward to using CF cards. CF is now finally becoming affordable as well. Really the proof is in the pudding, the 722 is very consistant, idiot proof and rock solid in the most extreme conditions (8hrs in 115 degree heat(direct sunlight), rain, a few spills and kicks), excellect manufacturer and community support.
I think the 7xx recorders are really in a whole different league than the Marantz, tascam and edirol units. You don't see any shortcommings till you start to compare them to the zaxcom and cantar, devices which are 4x more.
I would consider a modded R4 if the layout was was totally revamped or a modded 4 channel ~671 w/ a new layout and a HD. These probably will come available shortly after i move up to a 744 in a few years but I will not have any regrets.