+1 for the P8, test rode both when I bought mine from Thor. With the same tires I'm sure the difference is less, but I think the smaller wheels benefit from fatter tires (plus they are BMX size and it is easier to get tubes in a pinch).

Otherwise the Mu has a more modern look, which I liked but not enough to buy it. I think the P8 is the better deal but the Mu is still worth the extra $$

The only way to know for sure is to ride both.