A motherboard that has been designed for mining specifically will be by and large the most hassle free and the easiest to setup for mining with 6 or more GPUs with the least troubleshooting, hair pulling, and downtime. We came to the decision that at this point we won't use anything other then dedicated mining boards. Down time is lost money, let alone the aggravation of dealing with it and losing that time to do other things that need to be done.... they just aren't worth it for us at least.
In my year and a half of experience, Mining specific motherboards have given me WAAAY more trouble than regular or gaming motherboards.
I prefer the latter because of the ease of setup ( for a total newbie it may be more complicated to setup a non mining board, but once you know your way around a few bioses, its fairly straightforward ) and stability, because their availability is much better and because prices are much more reasonable.
Sure in the long run maybe the mining board has better components that would last longer, but I doubt it seeing the cheap ass thin pcb's and lack of features on both Asrock or Biostar (I own 20+ of each btw so I speak from experience).
Suffice to say is, if one of the reputed motherboard manufacturer make any mining boards, I will buy them without skipping a heartbeat. I await the Asus mining boards for now.
well, I put it fro myself very simple and straight - if I want stability to be the main thing - then PCI-E slots have to be implemented as standard feature by chipset
not by any external controllers or something similar.
that is why I choose MOBO which has 6 PCI-e slots built in
I can add 1 or 2 pci-e slot through M2 riser and that's enough for me
in the end I have a rock-stable system with nice performance and... in the end I can sell this mb easily
in EU there is bigger problem... prices are pretty high compared to normal mobo. And their desing is pretty much save on everything, they not put even control leds on them 
