I have recently changed to a T4 from the xxxt-cr. Here's what I have noticed. Here is why I think the T4 is better.
*Jumps and lands the big jumps better.
*Nicer diff assembly
*No more e-clips
*Easyer slipper pads to deal with
*There is way more aftermarket parts out there
*Simpler truck to make handle track conditions. Losi has too many holes to try and its easy to get lost in the set-up of the truck.
*Parts seem to be cheeper!
*I my area there are Team drivers. There help is priceless when it comes to set-up with track conditions.