I have to go with what's easy to work on, easy to tune, durable and parts availability. Does the bumper design function very well? I like the RXD because it comes with a good chassis for carpet, you can remove the spur gear and lower it for lower cg. I would have considered the X-Ray05 if they would have done the same as the RXD, but made a two peice bulkhead from the rear, so that you could remove the diffs quick as well. Not to mention you can only use their spur gears.
When X-ray designs it like this, I'll be all over it. Why won't a company design them this way? Six screws, the spur gear and diffs are out