Don't know your budget, musical genres you enjoy, or listening priorities. And don't know what you mean by "smaller single driver speakers". Do you mean smaller drivers or smaller cabinets?
In a room that small, you'll be listening nearfield if you and the speakers are properly set up (not too close to any walls). In that case the coherency of single driver speakers is a huge advantage in my book.
Any in a room that small developing its full deep bass potential won't be very hard, so a 6 inch extended range driver should be adequate.
I've not heard the smaller Lowthers, but the 8 inch ones are just too detailed for me. They "force" the analytical side of the brain to work overtime to the exclusion of emotive enjoyment. Nearfield would make this effect even worse.
If you settle on a mid sized driver like the 55s and want affordable, check out
http://www.geocities.com/rbrines1/. There's a few of us ACers that own his stuff. Bob's a pleasure to work with, his workmanship is good, and you can't beat the prices.