Thanks again all.
@yakbob - very interesting indeed. The Allisons also have a total of four large woofers (and four mids and tweets), and they do have a very relaxing, "east coast" sound. Hearing that your KEFs share some of these aspects, and yet the Spatials work even better for you, is encouraging.
I actually really love the way the Allisons perform in my space - for example, I NEVER experience issues with bloated or boomy bass, which from my reading here seems to be a common problem - but the idea of something more dynamic & live (and totally different) is appealing.
Thanks also for your thoughts Elizabeth, your opinion counts for a lot. It is strangely rare that speaker designers consider room interactions at this late date. If I may ask, what integrated would you recommend (used or new) that would work well, for say $2500 or less?