Of those i know who have gone through the system, it would appear that pp/ hour building etc is well served in the states, but completion or the IR/CPL is more likely than not, better done over here, after all its this airspace you are interested in working in!
You cant do your (JAA) IR there anyway.
Regards
CR
PS. You may wish to have a scan through the Prune and see what those who converted (FAA to JAA) licenses actually thought of it, rumour has it that a fair few people take a bit of getting used to it!