You can take what you have and improve it. We were doing that with Tamiya TUs 12 years ago and some of the results were astounding.
I can vouch for the quality of the TU's Robert refers to. I bought one of the ETO ultimate competition TUs some 12 years ago and installed in my new Tamiya Tiger 1. Tank weighs in at 19 pounds with many metal upgrades. It's got over 500 hours runtime on it. It's still going, I'd say it's just getting broken in...