With the exchange rate as it is, it will probably cost you very little more to get yourself an FAA IR in the States than it would to get an IMC rating here.
You will be taught how to do things to a higher standard, EASA can't take your FAA IR away from you and until such time as the IMC rating is phased out (if indeed it is phased out) then the CAA will give you one on the basis of your FAA IR.