I have the GS-300 with a TS .91 A good plane all in all. The .91 is a little underpowered for it, but it is 3D capable. I can't get quite enough control throw with the CA hinges so you might want to replace those, but I can TR. Knife edge figure 8's fine. Not enough rudder for KE loops though. Inverted flight is fine.
In my opinion a os 1.08 or something and a little bigger rudder with more throw there and on the eleveator will make this plane perfect.
The kankge kits are well made, go ahead you won't be disappointed.
RP