I tried out another Gut/Beast hybrid this week. Again, very happy.
So far I can't say the 400T is very string sensitive, but I've been most satisfied with the Classic gut /Beast and SS/Classic gut setups. Decent, controllable power, adequate spin, comfort, and I believe better for an all-court game.
I wouldn't mind trying some Beast in the x's. I haven't seen much difference between putting gut in the mains or crosses, but haven't played them simultaneously.
Steams 99s, leather grips; 4G @58lbs; ZX 16 / marathon 15L @62lbs