If it were me, I'd spend the least amount that I could to get the features that I want. My current receiver cost me $450. Granted, I ended up adding an amp that made a nice improvement, but my speakers have a sensitivity of 85 dB, which is a lot lower than those Klipsch that you are considering.
I bought bleeding edge once. A $1000 Yamaha that was the first with Dolby Digital to hit that price point. I was so happy, but within a year, you could get that and DTS for cheaper.
My current buying philosophy is this: buy a mid-level receiver that has the features that I want, and within a year or two, I can buy another mid-level receiver that has the same or more features than today's high-end receivers and have the total cost be the same or less than if I bought a high-end receiver today.