jschleer - If you're asking about the Vantage carbon fiber chassis...
Vantage makes (made?) two chassis for the Revo.
One for the 2.5, and they came out with an extended chassis once Traxxas rolled out the 3.3.
Both are well made and spot on concerning measurements - everything fits as it should and you're not drilling or grinding away to make parts fit.
I haven't run into any issues with it being more "fragile" than a stock chassis, but they do flex a little where the stock chassis does not.
For example, I had a carb on a Siro 23 that due to slop/tolerances would stick and it wouldn't open to full throttle.
The servo was strong enough and the carb sticking was bad enough that you could see the chassis (motor mount) flex. This messed with the CB/Spur mesh.
Everything was fine once I replaced the carb and dialed in the throttle/brake endpoints.
So having said that - I like having an extended chassis Revo that weighs 8 3/4 pounds.