I have a 10X24 room and I had a dual 20-39 setup. I never got "quesy". These things you read are just exagerations. I now have an HGS-18 and I feel that BASS More than from the dual SVS BUT none make you sick or "quesy" - Its just good clean bass from both SVS and Velodyne.
I think this will tend to be dependent on the individual to some degree. Like sea-sickness and car rides.
My ears are extremely sensitive to air pressure changes(probably a sinus cavity thing). I don't think my hearing is better than average on the whole...but I can *hear* stuff others usually cannot.(the distint approach of a large helicopter for instance).
Loud bass doesn't make me quesy, but watching some of the DVDs that have the loudest bass often makes me feel sick...