I have a stone/stone brute, now 26. Accuracy is generally not that good until you get Acc DOs/SOs in the attacks, but after that they are fine and awesome. Can't say I noticed the mallets being particularly bad though. Still that could just have a lower base accuracy to ballance the high damage.
I love the set and it really is smashtastic once you get the high damage attacks
Seismic Smash for teh win !11!1!!!