An IOM aircraft registry would have considerable advantages to residents on the island, I would imagine. As with yachts, etc.
I also guess they can't upset the CAA all that much... well not for the time being.
I mean, look at the rest of the new EU members - any of them would make many millions by the simple expedient of accepting FAA licenses and ratings (and certification) in their own reg planes, with the addition of having no ownership or residence requirements. This would rapidly terminate most of the N-reg scene and its daft trust arrangements; almost nobody would bother to be on N-reg if they could do something simpler.
But, so far, nobody has had the ba11s to do this. I am sure they have been leant on heavily. There is so much politics in this game.