Here is my opinion on the subject.....
A fully balanced design (ie input to output) is absolutely the superior design from a technical standpoint. That isn't open for debate. It is, however, more expensive because it just about doubles the parts count.
Now, for just about all consumer applications, it really isn't going to matter at all. Single ended is perfectly acceptable in most all consumer applications. So a balanced input may be a step up from single ended and a step down from fully balanced, but the end results are gonna sound the same (in general).
The problem for me is that slapping an XLR connection on an amp and not building a fully balanced amp circuit is kind of misleading. To me, it seems like they are trying to pull one over on the customer that doesn't know better and doesn't understand that an XLR connection alone does not make the amp fully balanced.
For the record, I am absolutely a fan of Parasound! I own a 1206 that has been flawless performance, with no music playing, I can crank my USP-1 to full-volume, put my ear right on the tweeter, and hear absolutely 0 hiss or hum! I think their price/performance is dang tough to beat, and there is plenty of used Parasound on the market that makes them hard to pass up.
However, I am more of a fan of their new classic (or truly classic) line than the Halo line. Sure, the Halo line is a step up and looks very good. But it's that dang XLR input without the fully balanced circuitry that kills me on those. IMO, if you're gonna put XLR on there, then make it fully balanced! Don't try to fool me with it. I'm not just bashing Parasound here, I believe Marantz (and I'm sure many others) does the same thing. And, like I said previously, as long as you understand what you are getting for your $ then go for it!
As far as ATI, after I saw some pics under the hood and the build quality, I am absolutely sold!