It looks like good. I know that the B75 famili chipset does not have the Intel rapid storage, nor smart report technology and Intel Vpro. But are those features really necessary ?
No, they're only necessary if you have some specific requirement. For a regular gaming machine they're not necessary at all.
As for mATX, the mATX boards often have fewer features than the ATX versions, but there usually isn't any performance difference. Overclocking may be more restricted with mATX boards though, since they often cut down the VRMs.