Well, you might be fine with a 10oz shocky if you are lucky enough to have an extremely large gymnasium.

Alot of us are flying in gymnasiums that are one basketball court sized, and about 20ft ceilings. You can fly a 10oz shocky in this sized gym, but you wont be able to do the maneuvers that a 5oz shocky can do in that space.

For instance, I can do a reverse cuban 8 in a space of about 15ft, and never get any higher than 10ft with a 5oz shocky. Id never get close to that with a 10oz shocky.

The other thing is that you cant slow down a 10oz shocky like you can a 5oz shocky. A 5oz shocky will cruise around level flight at about a brisk walking pace. A 10oz shocky will need a high angle of attack to slow down that much. In a small gym, this can mean the difference between "flying" and "fighting".

Its kinda hard to explain to someone that hasnt experienced it yet. You really have to get your hands on a light shocky and a heavy one, and take them out for a test flight in a small enclosed area. Then you'll quickly find out why we all strive for extremely light weight.

Basically heavier planes fly faster, and require more space to do maneuvers. The extra speed makes it difficult to keep from running into the walls, ceiling, floor, bleachers, etc. And during maneuvers, you'll quickly run out of space in a small gym.