N-reg flying
I am investigating doing just this - buying an N-reg and flying/basing it here. The most obvious advantage apart from buying cost (and choice!) is that it's a lot easier & cheaper to get an IR in US.
Also note that there are a number of trust & financing companies (most based in the Channel Isl.) that seem to be specialising in this area.
Andrew - I am curious by your "needing an FAA certificate to fly it outside UK-airspace" comment - please explain.