All my flying training including multi was done off grass, between 750 and 500 metres. I think a lot of the problems stem from instructors with very low hours and having no real experience themselves, and having learned on tarmac. It was always great fun to watch the visiting pilots on QXC fly in and do go-arounds or even end up in the hedges, and it all seemed to stem from on signal issue: used to miles of tarmac with high braking efficiency, they do not land on the numbers at a sensible (slow enough) speed. How many do you see touch down way beyond the numbers far to fast. Ok if you have a mile of tarmac left, but you get a 100 metres of so after the numbers on a 700 metre grass strip, and it can get very exciting, particularly if you are fast, and the grass is wet.