Subwoofer to go with Triangle Celius

I'm searching for a subwoofer to go along with the Triangle Celius. I'm considering going with the Triangle Sub for the match but, searching for other options also. I'll be using the system 60 / 40 for home theater vs. music. I would like to spend about $700 for either a new or used sub. All comments and opinions are greatly appreciated.
Paradigm Servo-15......
I'd think about a Rega Vulcan (made by REL) or an REL Strata II or III. They're both very musical and could probably be found used in your price range. I haven't had the opportunity to hear the Triangle sub though.
I recently visited with a Triangle dealer,his opinion was that the Vandersteen Sub with 3-8" woofers and a 10" passive sub radiater was an excellent choice,I believe the price new was about $1200.His thoughts were that it was better than the REL!
Here are a couple of websites to take a look at: and Both have relatively inexpensive subs which have been getting great reviews.
Has anyone heard the Triangle sub yet? I dropped by the Triangle dealer and he was out of stock.

Musicmann, did your triangle dealer recommend the vandersteen over triangle's sub?