I find with guns, weight and balance has more to do with how well you can carry it rather than size. It also depends on the layout.
For example, I find a G3-SG1 rather uncomfortable (too long), yet my G36 is fine for me, and it's actually longer (stock to barrel) than the G3. The difference is the stock is shorter, so the reciever is closer to your body. It "feels" quite different.
The best thing you can do is get out to an airsoft game and ask some people if you can handle their guns. Honestly, you won't know until you do.
"Someone in a Prius tried to race me at a stop sign the other day. I couldn't believe it. I had him for the first 100 feet or so but I can only walk so fast."