Reading Broadie's book "Every Shot Counts". Lots of interesting stuff in there, but one was that statistically, large cups narrow the gap between good and poor putters.
Obviously, good putters won't like it.
I know Broadie is the real expert on such matters, but I have to wonder how he managed to accurately evaluate the effect of long putts that barely miss the hole.
Imagine, for instance, a putter like Jordan Spieth, who makes a much higher percentage of long putts than anyone I've seen. A lot of his long-range misses have to barely miss.
If they are within 1.5 inches of the cup, they are going in. Poor putters misses are less likely to be that close.
Also, having played to eight-inch cups a bit, I think that you'd never see the real effect without letting the players adapt to big cups. Great putters will soon figure out that their lag putting skills will result in a bunch of one putts