Awesome write-up Terry, very informative. Thank you!
Side-note: I'm sitting here at home, took the day off work, waiting for my GR's to be delivered in a few hours...and for the SE's to be hauled off down the block to my dealer's
I'm definitely a "tilter" with the SE, using plain hockey pucks, but I've thought about something more solid like the HRS Nimbus. The height of stage, as you noted, is just 1 reason why I need to either tilt or engage supertweeters.
The ST100b is something I use only sometimes with the SE. When I can sit
directly in the sweet spot, they aren't as necessary, plus the overall coherence & musicality of the Tannoys is best (by a hair) with them disengaged. However, the ST does seem to extend the sweet spot a bit, which helps when it's both my girlfriend and me listening. I think it's pretty clear that top-end extension and off-axis response are slight weaknesses of the Canterbury SE -- exacerbated by the lower-than-ear-level horn tweeter!
The Canterbury GR probably changes the game a bit with its better extension up top; not sure how well they'll work with ST100b -- and I'm sure the new GR ST has a much smoother, cleaner response too (plus they look so cool). At least I know I'll definitely have to dial ST's down from the 14kHz / 95dB recommended for the SE (a bit hot even for SE, but usually I'm off axis when they're engaged anyways).
Love that you run 2 big subs with the Canterbury (Jim Smith of Get Better Sound Fame does this with his SE); that will be something else for me to consider in the future!