Like i said to Jay, i've met Mark many times and he's a genuine good guy and his workshop etc is professional too, i've only met Garth tbh on a handful of occasions and he also seemed a genuie good guy.
I have never had work done by them so can't pass comment, BUT going by their race car and own cars i wouldn't hesitate.
As for the RK, Abbey etc i don't know them at all so can't comment