Played with it a bit more today. This time I counted the shots: 85 good shots from 220 BAR down to 95 BAR.
I haven't traced out the power curve yet, but (10) chrono readings at sporadic intervals indicate a 7 FPS variation with weighed JSB Express. After I ran out of Express, I tried the trusty AA-Field, which varied only 4 FPS in a 10 shot string. I'd say the regulator is working to my satisfaction.
Tried reversing the palm shelf; you're right it's better that way for those elevated standers and neck-breaking elevated prone shots.
So far I have been shooting in the cold, around 4 degrees C, maybe when it gets warmer the power will rise a bit too!