Your plane is tail heavy because you are using too light of an engine. I'll bet your vertical uplines could be better also. If you add a pound of lead to balance your plane, your verticals are gonna be even worse. You may not even have unlimited vertical at that point.
I flew mine with a Brison 2.4. On this plane, you cant beat a gasser combo. If you want best performance, and want to REALLY enjoy this plane, keep your eye out for a good 2.4 Fox/Brison, or BME 44/50 engine to go on sale somewhere.
The Sig 300XS is an amazing aerobat! You'll love it!
