rustle
Great scheme! So if you have an IMC and (say) over 20 hours of instrument time and want to get a JAA IR, then either:
a) you do an FAA IR first (20 hours) then a JAA IR (15 hours)
b) you just do a JAA IR (50 hours)
So to get both licences you need 15 hours less flying than to just get the JAA licence. Fantastic. Who makes up these rules??
(Before anyone points it out I know that this is slightly simplistic as to get an FAA IR you first need to pass an FAA PPL skills test, and you also need to do the FAA groundschool, etc).
Or, to put it another way, if you have an IMC and want to get a further instrument qualification there is no reason NOT to do the FAA IR first.