A couple local racers have run them. I wanted one when they first came out but I just kept my XX4.
There were a couple issues with the first units but I'm sure they have been addressed now, and there are hop ups like aluminum motor plates etc if you need something upgraded.
It's a poor man's Kyosho/Yok/BJ4... and there are some satified SB owners... like Cain at
www.rc10B4.com