Simply, a motherboard doesn't effect gaming performance, as they all should have a PCI-E X16 2.0/3.0 GPU slot.
Only advantages are, as you listed on is SLI/Xfire.
More you spend, you'll generally get better muti-GPU support, with SLI/Xfire running in X16/X8 or X8/X8 (same as first), with triple SLI/Tri-Fire, X8/X8/X8, X16/X16/X8 or cheaper boards with X16/X16/X4 or X8/X8/X8 and Quad SLI/Quad Fire with; X16/X16/X8/X8, X8/X8/X4/X4 ect..
But with motherboard there are chipsets also, better the chipset the better OC capabilities of your CPU, curruntly with intel 4th gen LGA 1150 CPU's you get this selection of boards; H81/B85/H87/Z87, Z87 is the only one that has a truely 'unlocked' capability for the CPU as if you have a "k" processor in a H87 board, you'll only get a limited OC whereas Z87, you'll get a full 'unlock' on OC.
Also, the more you spend the more features, i.e. USB, SATA (to a certain point), and supplier on-board features.