There is no need to flash a custom ROM, however I recommend replacing it after you get your phone working with cricKet - I used verizon's stock for about a week, but I found this Liberty ROM which is great
Liberty ROM 1.5 Released for DROID X/2 - Droid Life: A Droid Community Blog
, fast, good battery life and eye candy, highly recommend it. Ohh one more cool thing......after you get verizon's stock rom working, when you flash to a new rom there is no need to ajust APNs or anything, 3G works right after you flash it....pretty cool huh, One more tool I would recomment is TITANIUM BACKUP makes upgrading to a new rom MUCH easier....
