right off the bat the ZX5 is definately the more complete racer, its been designed with top drivers, but no one knows who has worked on the Impact.
I'll not let that prejudice the car though, im really looking forward to it.
I'm just putting the finishing touches to the X5 review, the yokomo BX review is largely written up also. So, hopefully some time next week I can start on the Tamiya. I know people already built / raced the thing, but theres no point me rushing into it and doing a half-assed job of it, I want to push each review to be better than the last if i can.