Does anyone use the Silverline Audio SR 17 speakers? If so, how do you like them?

All of the reviews I've seen are 3 to 10 years old, and I almost never see them for sale used. Are people taking them with them to the grave? Are the owners staying current with updating them as the hardware changes and not selling them? I have begun re-assembling my old analog system, but in a smaller room, and I think they would be ideal. No dealers in my area that I know of (Oklahoma) so trying a pair out before buying might be difficult. Your thoughts?
I'm in the same boat as you,looking at the Prelude+...1 single pro review from 4 years ago.Maybe the fact that we don't see them for sale here or fleabay is a good sign...
They must be really good. Six or seven years ago I would see them for sale on a regular basis but then it dried up. During that time I was changing speakers fairly often and they were always one of the candidates. I wish that I had tried them.
freediver - I’m not a pro reviewer but, fwiw, I’m running Prelude Pluses. They sound great with tubes. Took a while to break in and playing with placement definitely helped with bass quite a bit. They image well and create a wide soundstage...outside the speakers. Front to back depth is very noticeable on some recordings. Nicely detailed without being fatiguing.  They are clean and clear sounding but not harsh or sterile.  Lyrics are easier to understand.  Previously "lost" subtle textures on vocals and instrument decay are conveyed.  They seem best suited to jazz (acoustic and electric), strings, female vocals, indie rock. That’s not to say other genres are unlistenable...not at all.  Just listened to FZ Waka Jawaka off YouTube, I was very enjoyable.  Black Light Syndrome  (Bozzio, Levin, Stevens) "Duende" is extraordinary. These speakers are "quick". A sub brings a nice upgrade to the sound but depending on your music preferences might not be absolutely essential.
I've had the "non plus" Preludes for a while and they are really great speakers. They're voiced for a relatively even tone that works for me with non screechy treble and great mids, and although the specs claim more bass than they actually produce in useful amounts, this isn't an issue as I use a couple of RELs with them. Tube amp magic in a relatively large listening room...Alan Yun knows what's what. 
The 17's are an excellent speaker and, as you have observed, they rarely come up for sale. I'm still waiting for a pair with the ESOTAR tweeter to appear. (I already have the Bolero's but am looking for a different tonal balance in a second room). If/when I decide to abandon that wait I would consider the Prelude Plus' currently selling for about 2K. 
I called Silverline Audio yesterday (7-5-2016) and actually spoke to Alan Yun. My question to him was about speaker placement for the SR-17s. For my room size (13 X 13 X 8) he thought between 2 and 3 feet from the rear wall and 2 feet from each side would be ideal, and no toe-in necessary. He considered the dimensions to be a mid-sized room, and thought the SR 17s would be a perfect fit. He was very excited about the latest iteration, the SR 17 Supreme. He thought the Dynaudio drivers were the best he has seen for these speakers. He does his own crossover and is justifiably proud of it. I'm In!