At this stage in the game with the CAA/JAA hand over to EASA I would strongly advise anyone against going the pure FAA route. All those who are on the FAA wagon now will tell you all about how politics with the Americans will prevent any major change for the future. The fact is that EASA want oversight of ALL aircraft in Europe and what is seen time after time is the Europeans seem to get what they want. Burying your head in the sand will not prevent this. My feeeling is that the small FAA aircraft will be forced out of being permanently based in Europe in the future.
If you are going to the USA for a license and really want an FAA one then do BOTH the FAA and JAA test.
The European IR changes are very close now with the report agreed at yesterdays meeting and due for submission to the head of PLD in 2 weeks. So the JAA IR will be more accessible pretty soon, certainly within the time-scales achievable by a new PPL.