The M18 is a pure performance vehicle that excels indoors. An 18R cannot keep up (in this area). Anytime an 18R has raced with us locally, they usually end up disappearing after a few weeks. As it is, they are meant for different purposes. A rally car is meant to be all terrain, but in doing so, it looses some of its ability to become the best at anyone.
BTW: There is another advantage the M18 has on carpet. Price of foam tires... by far!
You wont be breaking parts on a m18 nearly as easy as the other vehicle listed to even worry about parts availability. Craftmanship and EU made, have their advantages in this area.
Barring that, check the
dealer database as there might be someone local you can go through. Otherwise, there a great xray dealers you can order through online without using ebay.
In short, if your going to run this on a smooth surface such as a tennis court, or full out carpet. The M18 is your choice vehicle. If your planning on running wherever you can, you might seek otherwise.