HAHAHAHAHA 23Hz from an 8" sub with 150w. Good old DefTech and their ridiculously overstated specs. Sorry, just had to comment on that one.
I've owned SVS and HSU subs and I whole heartedly recommend both of them. For a room that size, you could get away with a PB-10, but I'd still go with a PB-12 or a 25-31PCi cyclinder. The Outlaw subs were designed by Dr. HSU, so you won't go wrong there either.