I A/B/C demo'd a Infra-18, the Infra-12, and a Velodyne HGS-10 in the same room about a year ago at my pro-audio dealer...spent two or three hours dinking with them. I was really interested in the Infra-18 at the time as it seems like a lot of sub for the dollar.

Surprisingly I came out liking the Infra-12 a bit bitter than the 18, if only because it was a bit tighter and similar in the amount of "depth" you get from the bass associated with large-cone woofers, but neither had the sharp response of the velodyne (though the 10" didn't compete with output). For music at moderate levels though, I'd say the BAGEND's are just dandy as they do indeed go quite low on the frequency sweep. The Infra-12 is quite amazing though and takes up a lot less room...that Infra-18 is huge...I'd give the 12 a demo if you have the option.

Cheers,

-Derek S.