Miscellaneous thoughts on first reading:
1) There is such widespread interest in XT1086, it would be disappointing not to have the full Monty on it. I'm saying retest, if you have to. Also, while trying to make it into something else may be fun and interesting, it is what it is, whatever that may be, and uber-tweaking is not gonna mainstream, even in DIY.
2) I've tried to argue for clarity on the concept of HT in other threads here: there's a subwoofer, and having 15" woofers in the mains is an unnecessary compromise in the interest of what? It's 3-Pi should be the focus, and Wayne's apparently working on upgrade options for that design, including TD12M. There are also three levels of JBL woofer alternatives for consideration, and any of them will provide the improved midbass many seem to crave. It don't have to be ugly, either.
Footnote: look what JBL's using in Synthesis One Array mains -- dual 8s:http://www.jblsynthesis.com/products...=US&Region=USA
3) C'mon folks, one sub's not gonna get the job done, no matter how we cut it; get with the multi-sub program.
4) Round axisymmetric waveguides are irrational. Square ones, too, but less so.
5) 8-Pi would be a corner alignment, I believe. It's also the one Wayne most likes, apparently.
6) Aluminum? JBL still uses it, but dusts it with Aquaplas in consumer applications. We know for a fact that mylar and kevlar diaphragms aren't operating in breakup mode to produce VHF and UHF, do we?
7) I forget, but I'll punch it in later....