Mugen, if there is smoke there must be fire!!
The choice is yours, do you want to run the risk of investing cash on a car that you need to spend hours trying to keep running on a race day, or invest in a car that works out the box and is proven. I love Mugen and run a X and have been for years. Will stay away from the MTX4 though.
At the end of the day it does not matter how good it looks but what it will do on the day. And there is nothing more frustrating for racers stripping gears whilst running amain finals, and I have seen plenty of MTX's do that.
In terms of support, keep the practical amount of running spares, dont switch brands 10 times a year, stay on the track... you will be ok.
Capricorn and Xray. the bonus is a Capricorn looks the part though.