Last month's issue of Petersons four wheel and off road had a nice article on mud tires. I think you can get to it on their web site. The Pro Comps did pretty well, but I might look into the new Hercules tire if I can ever wear out my BFG's. I have used Hercules tires before and they are inexpensive and hold up pretty well. They got a great review from Petersons.
I run the Procomp X's. So far I really like them. Handle great in the slop and the rain. I haven't taken them to many rocks yet. Other than on some small trails. Very little road noise for an agressive tire. Little to no wieght to balance them. Just rotate them and you should get good wear out of them.
the xterrains have impressed me no matter what the terrain is I have ran these tire"s through mud,snow,loose dirt,soft sand lots of rocks rain and believe me the streets out here gets slick when it rains out here all the oils come to the surface
the mileage has been very good
and if you had read jp magazine last month they gave them equal rating on all terrains