For what its worth, I am a very strong B or low A player. I have played on tons of Valleys and Diamonds. Overall, I would say that there is zero question in my mind which is the better table: the Diamond. Here are the differences as I see them:
Diamond has:
- better, truer rails
-tighter pockets with MUCH deeper shelves. This means you need to shoot the ball in the hole. This means this type of pocket favors the "better" player.
-nicer rails and pockets. The Diamond is much smoother along the top rails, there is no chunk of metal to avoid near the corner pocket. Also, the construction of the rails and cushions eliminates that extremely annoying condition that develops on Valley rails in which the cushion cloth is ever so slightly below the plastic top to the rail, creating a wonderful device for shaving down the shaft of your cue. I can tell you how many times I've gone to bridge on the rail, only to feel this sharp lip scrape at my cue, and need to change to a bridge *on top* of the rail where I really would not have wanted to do that.
Now, the question was which one do you play better on? Hmm...lets see. I certainly pocket balls better on the Valley, since the pockets are giant buckets. However, my opponent will gain the same benefit. I tend to play well on tight pockets, so I feel I have more of an advantage on the Diamond. BTW, I think the stock Valley corner pockets are like 5 1/4". HUGE! Anyway, the other major issue is the consistency. Every Diamond I have ever played on played at least good, if not great. Some Valley tables have played good, maybe even great. But many have played terrible. I believe the design of the rails (the bolts on the side to secure the rubber to the rail) is not the best. Go up to any Valley table, remove the little metal strip on the side, and see how many of those rail bolts are tight. It is rare that more than 1/2 of them are at any random time. This means each rail will play differently.
I know my best performances have come on a Diamond. Still, I think if I were to have a rack running competition, I might do a little better on the Valley, assuming it was set up the best it could be.
Overall, I'd still rather have the Diamond by a huge margin.
KMRUNOUT