Instead of purchasing a C1, I bought a pair of B1s to match my front main B1s. I experimented with using one vs. two B1s, portrait vs. landscape, T-M vs. M-T, below vs. above vs. both sides vs. both above and below my 27" TV. The greatest difference that my old ears could hear was in the higher freqs. These are the setups that pleased my ears the most:
Best: One B1 placed upside down (portrait, M-T) on top of the TV. No WAF, yet (moving the speaker behind the TV on a stand or shelf or wall mount might gain WAF).
Better: Two B1s placed end to end with their midranges next to each other (landscape, T-M-M-T). I wired these in series since my amp cannot handle 4 ohms. Not much WAF either.
Good: Two B1s placed one on each side of the TV (portrait, T-M), wired in series. This has WAF.
Hope this helps someone or at least encourages some further experimentation towards finding the ultimate location(s) for B1s as center channel speakers.