Having studied and flown under both the JAA and FAA systems I can honestly say that there is very little difference in the practical standards required by the two bodies. The real difference is in the theoretical knowledge requirements. You are correct that you can convert your FAA licence by taking the JAA writtens and practicals but did you know that you must attend 650 hours of groundschool before taking the 14-odd written exams! Oh,if you are a multi-thousand hour foreign ATP holder you only have to take the exams. Of course, it's all in the interests of safety and as we all know, bookwork is much more useful than practical experience - you should find that comforing next time you are flying in Europe with a 200 hour bookworm in the right hand seat of your Airbus!. .However, this still doesn't answer my question - how are JAA flight instructors training in the States without converting their licences?