To answer a bunch of questions:
3.4.2 comes after .340, its the newest build from motorola for the DX, it has not been officially realeased yet. I've not had any issues with flashing apps and there is now a few fixes to get swype working. No roms have been built off this yet, and it is very very stable and seems that the bugs are all worked out. Overclocks VERY VERY well. Battery life has so far been better then any rom i've used on the X
Like stated above its basically like having a stock phone. You need to go through the whole bloatware removal again and it must be deodexed before themes can be flashed. From my understanding, if you wanna go back to .340, you can flash maderstock or SBF back.I would hope that the next versions of our favorite roms are built off this