Simply put :::
Mix A = STR, AGI, VIT + 20 (first 3 stats)
Mix B = DEX, INT, LUK + 20 (last 3 stats)
Mix C = STR, VIT, DEX + 20 (1st,3rd,5th)
Mix D = AGI, INT, LUK + 20 (2nd,4th,6th)
... and of course their ND counterparts.
Pro's
There's a few different builds that would benefit
Tokens would be drained from the server
Donations may occur
Con's
(fill in the blank)