If you keep the aircraft on the "N" plate the CAA will have no involvment in the technical aspects ,however it wont stop them doing a ramp check on you , so remember that to fly IFR in europe the aircraft radio kit must be FM immune despite the fact that it is not an FAA requirment.
The FAA and CAA seem to work together on the checking of british based FAA aircraft and i,v been rampchecked twice by the FAA in the UK ,it was no problem to us as all the paperwork was in order but i,m sure that some might think that the FAA wont take an interest in UK based aircraft ....this is NOT the case !.