In a shameless piece of crossposting,here's something that anyone who needs a really tough clutch should look at...(they also do some lighter duty clutches).
I needed a clutch to replace my Sachs,which had finally given up beyond 440lbs,and Revo had recommended a look at Spec,so eventually I settled on a Spec Stg3+,which is a sprung full plate carbon/metallic clutch rated to around 570lbs,and looked about right.
AMDTuning imported one for me,and are also now importers for them,and aside from a problem with the first plate having an incorrect bearing,the rest of the fitting went well.
Now......how does it work in practice?
Having had a few paddle clutches previously,I'd been expecting Arnie's leg exercises from it,but instead it's light and easy to use,and once you're moving,it really does feel as easy as the stock clutch.
Like with all sintered clutches,it will grab a bit if you slip it,but really it is MUCH better than any paddle clutch I've ever tried.
Now the other thing that we all(myself included) think about when going from the DMF to an SMF setup,is the amount of engine thrash and vibration that's going to get through when the DMF is gone.
This really isn't anywhere near as bad as I thought it would be.
It's a little noisier than the Sachs but the clonking from the old DMF has gone so no complaints.