RE: MBX6T or HB D8T?
This would be a classic case of "you get what you pay for" I think. There is a pretty big price difference between Mugen and Hot Bodies. We have a local guy who ran HB last season and switched to Mugen for next season. He can't stop talking about how much better the fit-n-finish is on the Mugen. I've got both the 6 and 6T and I'm certainly impressed with the attention to the little things. Right down to the o-ring around the wire opening in the radio box.
As far as the D8T goes, it would seem you HAVE to cut some corners somewhere to be able to sell a truggy at just over $300.