i personally don't have any experience with svs, but they are very popular and highly regarded for ht. you may want to check out the speaker forum at avsforum.com any svs post will receive many responses.
I recently purchased the bottom-of-the-line SVS and matched it with my Plinius integrated/JMlab Cobalt speakers. The model is 25-31PCi and cost $549 + $25 for shipping.
SVS made their fortune appealing to the HT crowd but I love it for stereo listening. I haven't compared other models in my own home but, from what I've heard at local dealers, the SVS keeps up with everything I've auditioned up to $1,500. Effortless and powerful bass that is flat in my room down to 20hz. Very 'tight' especially when listening to well-recorded rock.
The cylinder shape does take some getting used to. WAF is imperative since it's tough to hide such a monster. My wife actually likes the cylinder look better than a boring box so I guess I'll keep her around!
They have a 45-day return policy should you give them a try. Other than shipping, what do you have to lose?
If you want the most bang for your buck you can't go wrong with the 25-31PCi. My friend has one in his system and it sounds great with both music and HT. Personally I purchased the HSU Vtf3 with the piano black finish for 799.00 plus free shipping. Matt black is 699.00. It's awesome for music but this thing shakes the structure of my entire house for HT. I like the variable tuning ports. 25hz for music and 20hz for HT. If you can integrate the cylinder in your decor the 25-31PCi is the best deal, but for me I prefer having the extra shiny black end table.
Re: AVS, they've been known for effectively sensoring anti-SVS comments. I think SVS provides a very strong price / performance ratio, but I would not match them with electrostats. I attempted matching a 25-31 CS with my CLS IIz LTD with little luck - the ported design just doesn't create a cohesive soundfield for serious 2 channel music.
Regardless of which subwoofer you decide on, I would recommend going with a stereo subwoofer configuration; especially with electrostats.