Anyone upgrade driver in older Velodyne?

I have a Velodyne 1250X sub, which includes a 15" passive radiator. This sub is tremendous for movies (it moves my listening chair from 12' away!), but I very rarely watch movies anymore, it takes time away from music listening. This sub is lousy for music, though, with boomy and bloated sound. I am considering upgrading the driver, and probably sealing off the PR, and retaining the existing 250W Velodyne amp for now.
Candidates include the Titanic III, SVS, and Rhythmik
Audiio DS 12TC. I'm just wondering if anyone has tried this, and with what measure of sucess?
Thanks for any help,
Enjoy, Dan