I race my T-Maxx, and I take it quite seriously. That is the reason I run the 2.5 plastic sliders. It is for pure performance. You gain over 4 ounces with the CVDs. That will slow you down, regardless. The original sliders were lacking, but the new 2.5 sliders hold up excellent under any smallblock power. Yes, they will eventually wear out, but they are relatively inexpensive to replace. They also require much less(none) maintenaince than CVDs. Without proper maintaince, CVD's will wear rather quickly. If not maintained properly CVDs are more likely to fail than the sliders. When they do wear out it costs between $15-$20 to rebuild one CVD axle.
Yes, most high-end car kits come with CVD's in one form or another. Although, if you will compare a CVD from a 1/10 gas truck to a CVD from a T-Maxx you will see a staggering difference in diameter and length. A stadium truck uses two CVDs. The T-Maxx up to six. That is triple the weight, and that is not accounting for the size differences. It is easier to justify the added weigth of CVDs on a 1/10 stadium truck, which generally have a higher power to weight ratio than the T-Maxx. Most 1/10 scale onroad cars use CVDs. There again, a huge size difference in the CVDs. Plus, most are made of something lighter than steel, such as aluminum or composite.
I admit it. I too fell for the CVD marketing hype. I bought a set for my first T-Maxx. They eventually found a home on my .21 T-Maxx. Since I went back to smallblock power, they set unused. I've since seen the error in my thinking. Lighter is better.