I have to admit Jon, I never understood the fast greens is easier argument. Assuming the greens have some movement and contour, and they are truly quick (for me that means 11ish whereas 9-10 is the speed I would rather see on firm, true rolling greens) my take is....
1. If above the hole, putting is far more difficult.
2. If level with the hole, putting is far more difficult.
3. If below the hole and not too far away, putting is easier.
Same could be said when chipping from any of the above positions.
It is difficult to say about approaching because usually I associate quicker greens with wetter greens and therefore easier to approach. Though, I am told some clubs get greens flying and firm...only experienced this once at Brora and the greens were crusty/bumpy...so not ideal. I think the last time I played greens which I think were too quick was at Old Town...and that was marginal, nothing terrible, just unnecessary given their firmness and difficulty.
Granted, experience helps, but there is no getting around the idea that large areas of greens are no go zones when greens run fast. I grew up on undulating greens that were quick, and I always knew right away when I was in trouble after an approach. Often times, there was no way to stop the ball...that of course means that eventually you become gun shy about attacking flags...often leaving tough two putts.
Ciao