DFC,
Its so depressing that someone with obviously so much experience and knowledge has the image you give of permit aircraft.
The 1980's saw the start of the major revolution in volume, very high quality, kit production in the US, all based round certificated engines. After the Glasair and Lancair came the Vans RV series. Ther are now over 5000 RV's flying in the world, nearly all having Lycoming or Continental engines, only the very latest, the RV12 has a Rotax 912, now that they are certified. There are, of course many other types, but several RV10's are being built in the UK, with 260hp Lycoming 540 engines and 4 seats.
Of the 2000 PFA aircraft flying in the UK, many hundreds not only have certified engines but full panel of primary instruments and decent avionics. What is so wrong is any implication that the same limitations should apply to all of the very wide range of quality of permit aircraft.
You seem to talk with some authority in saying that the CAA will relax these limitations if shown that there is no safety issue. This does give me a crumb of comfort. But to suggest that this should mean satisfying full certification requirements must be absurd, especially given the excellent record of safety of this class of aircraft, and the lack of bad experience in the several countries which allow IFR in those homebuilts which meet specified, reasonable requirements.