I have an open floor plan similar to yours, own the PL Evo 300 poweram,p and also listen primarily to jazz at lower volumes at night. I've owned the Spatial Audio M3 TS which was open baffle but lacked the powered "subs" of the X line. Honestly, based on what I've read, I don't think the subs in the X line will do much for bass in your home. Same for the Trio unless you plan to keep multiple subs in the system. Although I do feel the Trio is the nicest PAP speaker in their lineup.
The M3s turned me onto concentric designs, which led me to what I consider to be the British Cornwall...the Tannoy Legacy Arden. It's roughly the same size as the Cornwall and within your budget. They offer a great, full sound at lower volume and a well defined sound stage, and play well with long wall placement. About the only thing I can ding them on is a narrow sweet spot due to the point source nature of the design.