The stability issue was told to me by an ex-CAA guy with 18,000 hours of small plane experience and is more about positive stability issues way beyond what we normal pilots encounter in normal flight.
This was a conversation after he'd done some wonderful unusual attitudes in my RV-6 and thought it was an absolute delight.....
With Permit aircraft still unable to cross built up areas at any height despite my 6 cruising at 160kts IAS whereas an Auster or Chipmunk can legally do the 'able to glide clear' bit, I fear there are many rivers to cross on the way to Permit aircraft flying IMC - but good luck!