While those Yammies undoubtedly provide a ton of bang for buck, the price will be very comparable, in fact most likely even more expensive, if you needed 5-7 channels. At least compared to entry/mid Rotels, NADs, used Outlaws, etc. These other brands may not provide quite as much power, but there is something to be said for the convenience of not needing to find space, hide ugliness, use more outlets, having one chassis.
Even if I was more familiar with these pro units before I bought my NAD amp, I probably would've made the same decision anyways. I needed 7 channels of amp at the time to hook up to my pre/pro, HT was in the living room, and I was looking for 2 ohm stable amps. Im sure the Yam could handle 2 ohms fine... but y'all get my point.
If I was looking for a 2ch amp only, it would be a tougher decision. If I could actually hide them, the decision would be easier.