Yes, this is all in the last couple of weeks.
Hsu STF-2 was 599 CDN, PSB 6i was 765 CDN. Roughly $130 US difference. Arguably the STF-2 is closer to the 5i in terms of driver and cabinet size although IIRC it goes deeper than 5i OR 6i.
I have to admit I don't understand why a down-firing sub would be inherently less responsive than a front-firing sub. It's hard to believe that a one foot difference in path length could make a difference with a 30-foot wavelength, I agree.
I could come up with some explanations if you stuck me on stage in front of a surly audience but I can't say I would really believe any of them
