I have tried MANY tips on a break cue. I have found that of all the leather break tips, the water buffalo is by far teh best. Specifically, the ones that appear to be "WB" brand. I don't know who actually makes them, but that is what it says on the box. This "brand" appears to make two varieties. One is brown, almost a reddish brown. The other is black. The black ones are the ones I like. They hit quite hard, but offer decent control. Of course, these properties depend entirely on how hard you hit the cue ball. I hit pretty hard (20-25 mph). For me, this tip gives just the right amount of compression to yield high cueball speed and good control. I must say, though, that I have almost totally converted to either the black phenolic on my Omen break cue or more recently the Xtreme tip on my X Breaker cue. I still love the water buffalo, though. And yes, it can be somewhat brittle. You have to be certain to maintain a slight radius to the tip and maintain it so that it is not mushroomed. Also, it helps to have it not much taller than medium height. If it is very tall or mushroomed, the likelihood of a chunk coming out is much higher.
My $0.02
KMRUNOUT