I may be selling my current floor standers (Thiel 3.7s) for a smaller more mobile pair of speakers, and I can already sense that I will have to live with regret if I do it. In fact, the Thiels are a sort of return, insofar as I once had Thiel CS6's in my house and let them "get away." I always pined for that sound again. So I found my way back to big Thiels.
Problem with me is that, like too many of us, I can never be totally satisfied because of course no speaker (or component) is perfect and one will do things better than another. That's why I tend to have multiple speakers in the house at any one time, so if I get a bit to used to one I switch over to another for a while and re-appreciate them. Keeps things more fresh, but of course my wife will complain I have too many speakers (fair enough!).
My problem is I tend to regret selling whatever I sell. I miss that particular sound. Though I know one thing for absolute certain: I am never getting rid of my pair of MBL 121 monitors. I always lusted after MBL speakers but they were (and are) way out of my price range. I just lucked into a one of a kind deal to get these, and even if I don't listen to them all the time, I'm not letting them get away. (Unless I managed to get a pair of 120 to replace them somehow).