Westminster are beasts! I can only imagine the incredible soundstage. For my room, Canterbury’s are perfect. If this is going to be your first experience with a single driver, make sure you play with front feet adjustments to give you that required ‘tilt’. Depending on the height of your listening chair, the height of the mid-section of the Dual Concentric driver should be at your ear level. I was able to obtain better treble tonality and imaging with a slight upward tilt. If you want dead center pin-point imaging, toe-in your Stirlings.
I do indeed want pinpoint imaging, but I don't want EVERYTHING shoved to the middle, like a mono recording. I've found a bit too much toe-in can cause that, so I generally apply toe-in in very small increments over the course of weeks.
My current Lintons are ever so slightly toed in, and I find they can do rather better than advertised (or reviewed) at imaging and soundstage, with the right recording.
Where is your electronics rack? It was my observation that placing equipment rack beyond 22” height in the middle of speakers ‘interfered’ with imaging and messed with my illusion of DK playing in my room with her piano :-)
I'm set up in my living room, so the 2-channel has to share space with the tv, etc. The rack for my 2-channel equipment is more or less behind the left speaker, then there's a credenza next to it that stretches across to the right speaker. All of this is about 2 feet from the backs of the speakers.