Cows & Engines.... the syndicate I'm a member of have been operating a civvie G109B for a number of years to BGA standards. I'm happy to fly that and this hasn't
AFAIK, been operated to any sort of MAA regulations as there is no need to.
Being selfish I guess I should be glad that the civvie market won't be flooded by a mass of ex-ATC Vigilants but on the other hand, it does make any chance of a 'cheap' Rotax engine upgrade unlikely!