After a skimming, I think I agree with Steve; I am one that thinks one could choose a certain set of compromises over another when deciding between HT and music, and that is pretty much what I did for my two main rigs. (If I was TLS Guy, I'd want to have my cake and it, and I do agree that the ideal speaker can do everything well.) My stereo has extreme transparency, and the most important acid tests for them when auditioning were a cappella works written over a half millennium ago. OTOH, they are beamy, compress at higher volumes, with a tiny sweet spot. But I've never heard anything better for voice. Ever. I'm sure there's better out there, I just never heard it.
The HT is simply played back at higher SPL, in a significantly deader room, requiring greater dispersion, from greater distance, and at least the center speaker needs to overcome the attenuation of an AT screen as well, like yours. It's always interesting to me to see how much absorption the audience themselves introduce, depending on the number of people, and sometimes there are a lot of people. Also, HT tracks just don't require the extreme resolution of classical music, IMO, and I really believe that. Does anyone really know what a "spaceship blowing up in space sounds like"? Is Optimus Prime fighting with Megatron accurately rendered? When James Bond crashes his car broadside to take out a villain, is that exactly how it would sound in real life up close?
FWIW, rmk was running some very nice Revel speakers, and when he changed out to JTRs he didn't look back at all. The increased dynamic capability with lack of compression was totally worth it to him for what was only a minute compromise in resolution, I am paraphrasing by distant memory, but that is the gist of it.
Anyway, I was also once considering the idea of the ER18s for a front three. There are these bookshelves "about a foot tall" but apparently 14", not so cheap at a glance, but I think these might match well? Ask Swerd.
The Seas ER18DXT ported two way
The above said, it is generally and presently accepted that the surround speakers don't need to match, according to studies by F Toole, so far as I read on the intrawebs. I will say as a big fan of matching speakers, I wasn't the least bit worried of having mismatched surrounds if I had gone with the DIY upgrade to the front 3. If a mismatch is induced simply because the three most important speakers are significantly upgraded, then so be it, I don't think that's necessarily a bad thing. But like I said, matching is over rated apparently.