tweak1, you may be right...
You know the answer; only direct comparison would tell.
If I built 10 rigs with five speakers, and the competing amp performed at an equivalently amazing level as the XA200.8, and at half or less than the price of the monos, well, that would be news, wouldn't it?
But, my experience has been that is more a dream than reality. I do intend to get my hands on a GaN amp sometime. Will it upset the status quo? I have no idea, and neither does anyone else - unless they build 10-12 rigs. Just because it may perform better in one system doesn't mean it's a holistically superior amp. Most do not have that capacity to build a dozen rigs, and frankly, most reviewers don't want to be bothered (Imo, they also have poor methodology, wasting time on burn in when they could be discovering, as I do), and so and the anecdotal evidence will continue to swirl (and, perhaps, in a good way).
Frankly, even 10-12 rigs is still incomplete assessment. It would likely take a dozen more different types of systems to conclude it definitively. The preponderance of evidence is from very limited rigs with not much exposure to a wide variety of setups and speakers. Assessing Agon community's assessment of a product is like stepping into quicksand, no
bottom to gain support.
As an example of how complex it all is, I am working with a new tube DAC that does fairly upset the apple cart - that's my assessment thus far, having built about 4 of the dozen or so configurations I plan. Initially, my thought is that any system with this DAC would have a very unfair advantage in terms of performance. If a quality amp was being used with another popular DAC, versus a system with the new tube DAC, it is very possible that the lesser amp would shine more brightly simply due to the astounding capabilities of the DAC. So, reports of the brilliance of a particular amp or DAC, etc. when emanating from someone who built one rig have some weight, but the variables are so many that it is difficult to draw a reliable conclusion. When I build 10-12 rigs, I gain deep insight as to what's going on and how that component will tend to play out in popular use. That's the only way I see of gaining a more reliable assessment.
I am talking strictly in terms of performance, not budget. When fiscal considerations come into play, then the yardstick for assessment is a rubber band. Where the rubber hits the road, so to speak. :)