I recently purchased a Velodyne SPL1000-II. I assume that the 800 will sound very similar to the 1000. I really like the sound of this sub, I do tend towards HT, I probably listen 80% HT, 20% music. My previous sub was a JBL PB series which was a lot less tight and accurate, I can really hear the difference when playing music.
However I think that placement of the sub and proper settings of volume levels will also make quite a difference in how the sub will sound. I spent quite a bit of time getting the sub to sound right and experimented a lot with the placement. At first I had it tucked in a corner but that made it sound overwhelmingly booming. I have the same space considerations (that is why I went for the Velodyne in the first place) so the corner placement would have been ideal for space considerations. I ended up moving it away from the corner, next to one of my mains and it now sounds very impressive. The bass is always there, subtle but forceful when needed. So far I am very happy with the sound of this sub.
You mention magnetic shielding, the 1000 and 1200 are shielded but from reading the specs, the 800 is not so make sure to double check on that.
If at all possible try to audition the subs at home before making the purchase. This way you can see which one fits your speakers, room and musical taste.
Happy shopping!