The JAR IR requires you to do a considerable amount of groundschool (as much as 850 hrs dependent upon your start point) and costs a lot more (groundschool costs, aircraft landings and examiners fees several magnitudes greater than the US etc.).
The JAA IR is 200hrs of self study ground school and 2 days of classroom attendance. It is easy enough to do, you just need to get into the groove of study. Yes it is more expensive than the USA, but you are doing things on your own turf and for many of us that was worth the effort.
Once you have a JAA IR you can then do a foreign instrument written test somewhere like Farnborough and add it to your piggy back FAA licence. This will allow you to fly the N reg.
Under current proposals from EASA operators of N Reg aircraft based in EASA jurisdiction will be required to be dual licensed. If this happens or not remains to be seen, but the route mentioned above fits in with your desire to go the JAA route and have N reg privileges.