Timely thread, as I am currently going through this very purchasing decision. I'll be powering a pair of Onix Reference 1s as mains, a Reference 100 center, and using my old TDL bookshelves (for now) as the surrounds in a 5.1 system. All speakers are 4 ohm & low sensitivty, and I'm told the Ref1s are especially critical of upstream components, so I'm considering the amp section carefully.
I was seriously considering a Yamaha RX-V2700, but then I realized I can get an RX-V659 and an Emotiva IPS-1 for only slightly more money. Not sure about the 659 yet - I may go for a HTR-6090 instead (the "box store" version of the RX-V1700) as it can be had fairly cheap as well.
But either way I really like the idea of a modern receiver from a mainstream brand, since as others have pointed out, the big companies have the cash available to do the R&D on the pre-pro side, while it makes sense that a smaller, ID company should be able to provide a solid amp at a good price.
Of course, this is all conjecture on my part. Just trying to read between the posts, if you will. Perhaps I'll get the HTR-6090 & the Emotiva, and try the system both with and without the amp. I do like those 30 day return policies the ID brands have.