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.
PK Qtour 295, full YY 850 Pro (soon will be moving on to Steam 99s)