I've owned the same pair of CS2's since 1986. All previous comments in response to your inquiry are 95% accurate. May as well not be repetitive.
Thiel speakers are often mentioned as being revealing. They are! I think they pretty accurately reproduce upstream music material as well as amplification. I may miss a few points here as I am not nearly as knowledgeable as many on this forum.
I would not say they are warmer than Vandersteen's. I found Vandy's more "warm" than my Thiels.
Room placement is important to obtain the most from these gems. Thiel advises about 2 feet from a back wall. Damping in front of, on the floor, and sidewalls would help a lot. As you know many software programs exist the assist with this.
When I auditioned these they were in a totally carpet dampened room. Funny, carpet on the floor, walls and ceiling! :) Oh my the sound stage and imaging. I was seduced.......I walked upon to within about 2 feet of either speaker and the sound was riveted exactly in between them! Sound could not be discerned coming from the front of each speaker!
I should have taken note of the amplification. I suspect due to the type of folks at Berkeley audio that a pretty powerful tube amp was used. Sound was warm, rich, detailed, luscious but not muddled a bit. I was in love. Still am.
Bass: Jim Thiel, RIP, explained the cut off at 40hz provided the listener with accurate bass reproduction over the majority of available program material save for organ, where capacity dipping into the 20's is needed. Reading JT's description of his creation gives a strong feel for how much he truly cared about accuracy in audio reproduction.
I initially drove them with a Bryston 2B, only 50 watts. Sound seemed "thin, grainy, a bit hard" and had little strong bass. The 2B didn't have enough amperage to effectively drive bass units. 1994 came along and I purchased a Hafler 9180. Thiels are 6 ohm so I can drive 137 watts peak into them with sufficient amperage to bring out the bass. I suspect I could get even more bass using a higher current amp but I cannot afford the purchase and I am firmly committed to MOSFETS. Hafler as you may know has always been likened to more of a tube like sound. Would love to hear them driven by a strong tube amp.
So I think using an amp with enough current (maybe even a MOSFET type) and quality program material would showcase there bass capability to it's limit anyway.
Please excuse the ramble. Hope my additional comments help. I you have not purchased them, do! Hopefully the drivers are in good shape.