Yes Phil77, I do prefer the word "possible" rather than "definitely". I can't provide any maths because I didn't do "those sums"; however, I have heard a lot of anecdotal evidence from instructors converting FAA students to JAA and, in a lot of cases, it's been more than "a few hours". In a few cases, I've heard guys taking nearly the whole JAA course anyway!!! These instructors have no reason to sell JAA to me as going to the States to train was not an option (well, it was, but one I discounted pretty quickly for personal reasons); so, no axes to grind there.
Cheers
Whirls