The rear axle does seem to only fit the new Yokomo wheels with that big offset. But I guess this is still the prototype which will attend the worlds only by the team drivers. I doubt that Yokomo would put it on the market like this. If so, just drop in the R5.1 rear axle & hubs and your done for normal wheels...
Other than that, I really LIKE IT!!!
But we'll see once it is available...