Re: what on earth ??? a new kit ? upside down motor ?
I don't think it's a joke at all. And if there's any quality in that kit, then it's likely a good drive train.
The offset weight is not going to be enough to notice. That's based on my experiece with a Currie e-Zip anyway. The weights are likely to be close.
But I'd be reluctant to spend about $400 without seeing some track record. But maybe that'll happen.