Main difference is that after they 'visit' us the Classic guys want us to pick up and return all the bits - the F3 guys tend to just bugger off - I guess they need the time to work out the excuse
Best story along these lines was from an FF race at Oulton Park many years ago (so long ago that I was still a track marshal) - after a multiple car shunt one of the drivers said 'When you are sorting out the wheels - mine is the one with the good tyre!'