Might we persuade the JAA to pass a rule saying:
"A JAA pilot can use the privileges of a FAA IR on a JAA registered aircraft on a non commercial flight."
The FAA IR holders will be doing what they do anyway but no longer under 'N' reg, so less hassle for all concerned.
A great idea but it runs contrary to the European "superior intellectual" approach to matters. I have discussed it with a highly senior EASA official and he said it would be the hardest imaginable thing politically.
Current EASA strategy is to strip European residents of foreign license privileges in EU airspace (FCL proposal, p159-161) and they intend to fix the predictable uproar by signing reciprocal treaties with all relevant countries (which basically means the one which runs the vast majority of world's GA - the USA) for mutual license recognition.
Time will tell what happens. I have no idea but I think it was a political mistake for EASA to dig themselves in so deeply on this position because - short of a miracle redrafting of FAR 61.3 etc - they will be forced into a humiliating climbdown handed down from above (the EU Transport Commission).
BTW I would not regard an FAA IR to be an effective "shortcut" to a JAA IR. It may well be technically true, for some people who don't value their time, that doing an FAA IR in the USA, and then doing a JAA IR conversion here, is going to cost less than doing the JAA IR from scratch, particularly if doing the ME. The value of doing the FAA IR in the first place is if you have an N-reg plane to fly. If you haven't then I wouldn't bother.