SUB - Confuse?

Hello Everyone,

I am planning to upgrade my HT sub (Velodyne SPL-10)because of my wife and daughter's increasing CD listening time lately. They enjoy the current sub but I felt like I can give them better integration than what I currently have.
On this rig, I have a Sony CD player doing the work. On my separate dedicated 2 channel system, I have a Jolida JD100 and a Teres 255 as the source. Although my 2 channel set up is very good, my wife and daughter does not want to touch it. They will never subscribe to waiting for the tube cd player and preamp to warm up before they can listen to their CD nor cleaning the cartridge and vinyl before they can set the needle down to listen to records.

With that said, I've been reading a lot of threads and reviews about subs. Here's my confusion about my researcch.

1.) REL very musical, integrates well, easy placement. But why is it that there are so many people selling their REL's (Strata and Storm is what I am considering)? For 5 weeks (I've been making a tally), I've seen 9 Stratas (currently 3 at the moment)and 8 Storms in Audiogon alone.

2.) SVS - more power, "rock" your vowels to the max" approach. Musical integration for 2 CH a question?

3.) ACI Titan - Looks to die for, bulky, some reviewers swear better than the two mentioned above in terms of musicality. Why only few(base on reviews I can find) bought them compared to the above mentioned subs?

4.) HSU VFT-3 - the dark horse in the bunch with respect to price and aesthetics. very good performance and value ratio from reports posted by their owners. Too good to be true?

For simplicity sake, assuming that I will move this to my 2 CH set up of:
ML Ascents, Odyssey Monos, Octal 6A Triplex and ARC LS-12 preamps, Jolida JD 100 cd player, Teres 255 TT, Wright Sound WPP100C preamp, Lundahl step up, OL Silver arm, Benz ACE lo, and Acoustic Zen Hologram and Empirical Audio wirings

Which one will you choose? Please explain your choice if you don't mind.

Thank you very much and pardon the inconvenience.

abe