Definitely do not get the Reference center with the Synergy towers. I currently have a RC-7 with my SF-3 towers, but only because I'm in the process of moving front configuration of Synergy to Reference. The Reference and Synergy really don't work well together... mostly due to the titanium vs. aluminum tweeters.
I think that your equipment looks great, but I think that you could step up to a RF-52 Home Theater System and probably only spend $400 more than you were planning on spending. The Reference series definitely has a more refined sound when compared to the Synergy series.
The RF-52 system contains: 2xRF-52, 1xRC-52, 2xRS-42, 1xRW-10d
http://www.klipsch.com/products/details/rf-52-home-theater-system.aspx
Hope that helps []