I have a centerforce single friction in my rig and I really like it. It is easy to drive like a stock clutch. I don't see why anybody would need any more power. I have never noticed it slipping at all on me. Even dumping the clutch hard with both cases engaged in thick mud has never show any signs of slipping. I would be curious to drive a rig with a dual friction clutch to see what the real difference is. If the single is good, I'm sure the dual friction is better unless it sacrifices driveability.
I have a dual friction in my 85 4runner, and i put a single friction in my girlfriends 93. They are both nice IMO. Honestly it is hard for me to explain the difference without you actually driving them both at the same time. the only thing i can say is the dual friction i prefer for offroading over the single friction, THOUGH the single friction does a lot better than a stock clutch offroad. The DF just seems like it is meant for larger tires and the single seems more meant for stockers. The main thing i notice about both of them is that you can bring the idle down to 300-400 rpms without having to put the clutch in. I was never able to get that low with either of our clutches before i replaced them (both with about 2-3 years of driving on the stockers of unknown mileage, but mine wasnt going out, just upgrading). That could just be because both of the clutches were really old. i dont know. I think they are a great, albeit a little expensive clutch. I got mine through my buddy's shop rate so it wasnt as bad as i have seen some places charge though. Over all I would say they both engage very smoothly and predictably and neither one has ever slipped on us yet. I would not say the DF sacrifices any driveability. If I ever run into you on any trails around nor cal I will let you drive my truck around