Since I am not the techie type, I will try to answer Mfusick's question from a layman's point of view - there is no "best" design! Since each individual's wants and needs are different, different designs will fit the bill better than others. In your example, you mentioned that you wanted to limit the size of the surrounds to a 10" woofer. That is a design constraint which causes one design (such as Tux's new design) to work better than, let's say, a TD15M design which would require a cabinet that is significantly wider than Tux's. In my personal opinion, I like to match ALL speakers as much as possible, so if I constrained myself to 10" woofers in my surrounds, I would prefer to use the same 10" woofers in my LCR speakers in order to timbre match as well as possible. Does it make a difference - probably not, but it is just something on my "desired" list.
Now how about the person who wants something that has a high WAF factor? Well, maybe big SEOS horns in a big box might be a problem, but some wives may consider smaller horns in a taller, thin package to be cute - who knows.
From my research, it seems like the AE TD15M and TD12M are still among the best woofers made, so if size and looks are not a constraint, then a SEOS 15 horn paired with a TD15M, a suitable HF driver, and a well designed crossover, might be the "best", but I assure you that the surrounds will be big and heavy to mount (I know this through personal experience
), and if your ceiling is not high enough you might have problems with people hitting their heads.
The point of all this is that there isn't any one design that works best for everybody, just designs that work best for certain rooms, certain WAF, certain output expectations, certain sensitivity needs, etc. This is why I brought up Tux's new design to you - it seems to fit *your* needs better than most designs I have seen to date - high sensitivity, high output, relatively narrow package, great flexibility in configuration, and a great value for what you will get - AND you will also likely attain a very high degree of timbre matching throughout your system, something you will most likely lose if you use larger/different woofers in your LCRs.
Right now I am personally interested in Tux's design even though my current system is almost perfect (IMHO of course). I want to try out a new center that removes more of the spoken dialog from the horn and puts it into the midrange cone speakers just to compare to my current setup. I know it won't be timbre matched with the rest of the system, but I want to try it anyway...I just have a gut feeling that this is going to be a GREAT design, and might even launch a new breed of SEOS design concepts!
BTW, if you don't match ALL of the speakers in your system, I would strongly recommend matching the LCRs as much as possible, and then match all of the surrounds as much as possible separately. Try to match the woofers in all speakers, just in different sizes, as their tonal characteristics *should* be relatively similar. Personally (once again), I would stick with the basic same design from the same designer, just with different size drivers, waveguides, etc., as the designer would probably design his crossovers with similar sounding design goals.
Heck, the more I talk about this, the more I believe that Tux's new design is perfect for you...