(1) After many years I'm still waiting for the first glider, balloon or microlight pilot (all of whom use essentially the same medical as the NPPL) to have a heart attack and kill people. It has however happened in light aircraft to holders of CAA medicals.
(2) UK, USA and most other countries more or less automatically accept any PPL from any other ICAO country. The JAR-FCL license makes no difference to this at-all.
Largely I agree that, at least in the UK, the incorporation of JAR-FCL has been a fiasco, but get your arguments right.
G