Can't see any reason why I need to go for the added expense of getting FAA stand alone IR with the FAA CPL since I'm always going to have a current JAR IR and hence current IR on the 61.75 private licence. Hope that makes sense. Any views?
Because you can't add a based on rating onto a full FAA certificate. The moment you gain a full FAA certificate all new ratings must be full ratings and added to that certificate. You can't use the ratings on two different certificates to add up to one.
So if you are going to have to do both the CPL and IR and any other required ratings.