Which Harbeth?

7's and 5's...3's if you listen near field.

I have the same size room with C7ES3's and they're perfect for my room. I wouldn't go any smaller unless as Chashas1 said, you listen nearfield.

Don't buy Harbeths w/o listening to them (i.e., just based on their reputation). (Unless you buy them used and can resell them w/o much of a loss or if $$ is not an issue. They do resell quite easily.) Harbeths have a unique sound signature. Lot's of people love it. Some find it lacking in resolution, which is what I think is a necessary factor in high end sound.