Other than that, your advice is very sound: if you only want to build hours towards the PPL, but not do the PPL skills test in the US, make sure beforehand that either the UK and the US school you're using have a standing agreement (like Cabair and OFT, I suppose, have) or let your local instructor contact the school to arrange something.
Hmm. That's to make sure that the Record Of Training gets successfully transferred, and that the new instructor is confident of its provenance, right? Right now, I'm not sure where I'll be completing my PPL, because I'll probably have moved to the west Midlands later in the year, and it seems that all the flying schools with that kind of arrangement (Cabair, and Western Air at Thruxton, according to the CAA) are clustered in south-east England.
Not sure how I'll sort that one out, but thanks very much for pointing it out. I imagine that the CAA/JAA training outfits in the US without partnerships have encountered this problem before, so I'll discuss it with them. I figure I'll be able to make it work somehow.