I own the SHL5s and have listened to the 40.1s multiple times. You have a large space(22' x 25') and both SHL5 and 40.1 will fit the space well. Most comments by Airegin have been spot-on.
Before you commit to the 40.1s, I feel it would be prudent to at least try them in your room if it's possible. As with most speakers, it's all about managing expectations, more so with large full-range designs that pump out considerably more bass. More bass usually equates to more problems, and more effort is required to control bass resonance unless one does not mind some coloration. Interaction between loudspeakers and the listening room is crucial in this context, more so with the 40.1s. The Harbeths don't go too deep in the bass but their warm and full sounding bass may present some problems in certain listening environments, (some "boominess" in some rooms), especially the larger 40.1s with an additional 12" bass driver. Ultimately it depends on the type of music that you listen to or how fussy of a listener you are. One will be able to live with the Harbeth without any room treatments if expectations are low.
Good luck.
Before you commit to the 40.1s, I feel it would be prudent to at least try them in your room if it's possible. As with most speakers, it's all about managing expectations, more so with large full-range designs that pump out considerably more bass. More bass usually equates to more problems, and more effort is required to control bass resonance unless one does not mind some coloration. Interaction between loudspeakers and the listening room is crucial in this context, more so with the 40.1s. The Harbeths don't go too deep in the bass but their warm and full sounding bass may present some problems in certain listening environments, (some "boominess" in some rooms), especially the larger 40.1s with an additional 12" bass driver. Ultimately it depends on the type of music that you listen to or how fussy of a listener you are. One will be able to live with the Harbeth without any room treatments if expectations are low.
Good luck.