Personally, I was faced with a similar conundrum, I have two Heresy II's (vintage 1990) with new woofers and BEC crossover networks and a pair of 5 year old Heresy II's, so I put one of the older ones in as the center channel, set my receiver for 3 speaker mode, but truthfully, in two speaker cinematic mode, things still work well. The Center was icing on the cake.
The horns work and play well with other horns, so I figured that an HII center channel would sonically match my fronts....now for the subwoofer. I did have an entire R?-52 (RF-52's and an RC-52) system with the RW-10D, but the horns are just more sonically pleasing with me. Now I just have to find a good match for a subwoofer. Maybe Shinall...who knows ?
Any advice would be appreciated.
"You're gonna eat lightening and crap thunder..You're gonna be a very dangerous person."
Mickey Goldstein to Rocky Balboa
Enough Klipsch products, which only leads to the desire for more.