I think it could be a double edged sword:
For people like you Nigel who are very experienced GA drivers, I agree - this is another string to your bow...AND...your likes would probably use it to good effect. BUT I wonder how the less blessed PPL / GA driver would see this? Will it offer them another escape route into (possibly) worse IMC conditions? Would they be tempted to get airborne in much worse weather thinking they can simply 'pop' up EIR and alls well, forgetting or not bothering to consider the prospects the other end - ie - getting down below MSA to recover?
The sticking point is and still will be configuring the cab - too cost prohibitive for the lower end of the market, so I wonder how many could take this on?
Finally BOb - UK single engine IFR - NOT in your lifetime buddy!