My setup still has the stock replacement pads that came with the calipers and I have not run into stopping issues on the street. This includes hard stops from 70 off the freeway when playing on the ramps. Have not noticed any fade, but have not made repeated back to back high speed stops either.
I'm looking forward to seeing how well they work at the drag strip. The stock drum brakes would fade pretty bad (serious pedal effort) on the second quick turn around pass on the drag strip (from around 100 mph) and the third time (only tried once, very scary and somewhat foolish!) I almost went of the end of the track with both feet on the pedal. I don't see that happening with the current disks. Also, as Scarebird mentioned, there are other more aggressive compounds to try out.