Won't make any difference to most people, I have run dual licences since 2001 (FAA CPL IR and JAA PPL IMC) and just log my flights in one logbook. If you can maintain a JAA license then you will easily be able to maintain an FAA one at the same time (IR is rolling currency and if you maintain your JAA IR then by default the FAA one will remain valid).
As I could convert the IR relatively easily that would be an option. (I also have a Mexican visa stating that I am "a tempory resident of Mexico" on the back
)
But I would not go back onto the G reg now we're on the N reg. Had all this been around when our aeroplane was G reg then possibly we wouldn't have re-registered but I am pretty glad to be out of the "that will be £1000 please sir for your 50 hr" maintenance reigme.