mine balanced right on the dot with a os 46fx with the stock muffler (no counter wieght), i live a t a high altitude as well and mine is great,
You will find that the plane will grow with you, it is very easy to fly on low rates, but once you start pushing the sticks on high rated you will do things you never thought you could do, but be AWARE the plane can get out of hand FAST on high rates

I also think you should stick with the stock gear, it really comes in handy on a hard landing (the stock gear is extremely forgiving and will take the shock)

A.D.

good luck