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.
Current & recent affairs: PS97 (enjoying), ai98 (sold), Extreme Pro 2.0, Steam 99s, PK QT 295, Dunlop 3.0T (still like a lot) & Bio 400T