If you want to match the F52's now is the time, the new Performa line is rolling out and you should be able to find a deal on the center and S30's. I bought my S30's in white and paid around half price for the pair. Take a look at the S30's they are a very cool speaker especially designed for surround duty, you have a choice of bipole or dipole, they can be mounted right on the wall or ceiling if 7.1. Another money saver may be to get the F32 center opposed to the F52, the 32 is smaller but would be voice matched still.
I hope you are talking used for the Heritage, a Cornwall III is about $4k, with that you might as well get the Revels. If I were you I'd go with the Reference Klipsch series, the sound is more refined and you can match all 5 speakers. You would have a sub, you could use 5 Heresy's. They sort of look like a floor monitor.
Also, do you really want two sets of main speakers in the room?