I had 10's in the Logans, when I blew the orginals, the factory sent me some upgraded ones and the difference was quite noticable. I never could get the balance right in the listening area (a common prob with 'stat, plannar's), across the house we're talkin' serious bass tho.
The AR's have 8"s and are very nice in the lowend.
BTW, Martin Logan's Depth sub is one of the nicer subs on the market, powered, active crossover. Although Wardsweb *Luther* over at AK custom built one for his main rig, maybe have Lee or someone shoot him a PM over there and see what he did?