The only issue I have heard of with the actual belt system is if you get too much chassis flex that can cause issues with the belt. Probably why the chassis brace was a popular enough aftermarket item that AE came up with there own take on it.

If you use the exotek chassis, from what I have experienced, I didn't need the chassis brace.

The other issues were clicking diffs. Basically, using thicker shim(s) under the gears in the diffs solved that problem.

There have also been some issues with tightening down diff cases causing binding. I saw this on the factory team kit I had but not the previous team version. For that, had to back off the diff case screws slightly (and I didn't gorilla them down the first time either) till the binding went away.

Lastly, some have had the top shaft gear come loose from the actual shaft. That happened on a factory team kit I had. Its not very common though in comparison to the issues mentioned above.

There are others I am probably missing, but those were the main ones I personally saw.

To be honest, I think the main issue with the drivetrain is more so how much it takes to get to service it when you need to or you want to make an adjustment on diff fluid settings. Its definitely more involved than a lot of the other vehicles out there. But, after you have done it enough times, you probably will be used to it. I have also heard the process is really sped up using a power drill versus hand tools that I am accustom to using. There are also tips on the thread to get to the diffs quickly as well.

If the vehicle appears to be a good fit for the conditions you race on, I personally wouldn't let the issues mentioned above stop you from trying it out, especially if buying used since the prices on these are really low to get in on.