I can see why he didn't make that version, the casting was cruder and a lot more brittle that the definite kit.
It also had some fitting issues, but all these things can be overcome
Only thing it didn't came with wheels and tires...
The other difference with the definite kit is that on the prototype all hatches can be opened

My M25 for some comparison :



The prototype :


And how it came out. I'm still looking for some better wheels, but for the time being these will do.












