The P8P67 M Pro is essentially a reduced P8P67 Pro in Micro ATX form so while you will have reduced bells and whistles, you will by and large get the same performance. The P8Z68 V/V-Pro is a standard ATX board with all the features of a Z68 chipset. If you want the transcoding and SSD caching support of the Z68 then it is a better board to get and obviously more expensive.
Not many are M-ATX fans, particularly if the need is for performance, for the extra $30 you may rather want to get the P8P67 Pro.
so if i were to ask you to choose between e P8P687 Pro and the P8Z68-V Pro which one would you get?