I scored an Onkyo TX-SR608 in a thrift store a couple of years ago. Rock solid performer for my 1080p setup. Though I just went back to Denon, my Onkyo experience did not suck.
That said, for $230, the NR575 gives you 4k support and HDCP 2.2, so you can use it with a 4K tv. That alone makes it a steal. Go for it!