I use to have the "jagged edge" and upgraded to the TC-4. I was very happy with the results. Cant quote actual drops in temps but I do know that it was worth it (I think about 2-3C; dont quote me though)
I personally like the 4 mounting holes approach a LOT better than the clamps I had to use with the "jagged edge." That alone was worth the extra money, and the block just looked cooler