Had a diccussion with Vince, the owner of Totem last night. I posed my sub/Arro question to him and his recommendation was to go w/ Storm over Thunder. He explained that the Storm is a faster sub relative to Thunder, and consequently, a better match for the quick Arros. If wanted more sub volume in the room, he recommended two Storms.
BTW, Vince seemed like an unusually helpful and responsive fellow.