I’ve owned those Spendors and the larger Harbeth M30. In your size room I would keep the Spendors. BTW, you should stick with the LS3/5a type of speaker. The Harbeth P3ESR is my favorite shoe box size speaker. Here is one of many positive reviews!
directional speakers
I just bought a Bacch4Mac bundle and am thinking of upgrading speakers. Theoretica recommends speakers that are more rather than less directional. I currently have Spendor S3/5r2 speakers. No complaints at all, but I've thought of upgrading to Harbeth 30.2, Graham/Chartwell LS/6 or maybe Fritz Carrera BE. Love the BBC mid-range, but I have no idea of how to find speakers with a tight rather than broad sweet spot. Any advice would be appreciated.