I own both Thiel CS6 and CS2.4 as I am a huge Thiel fan, and I have listened extensively to the 5a. If I had the bux I would go with the Vandersteen simply because the bass alone is unparalleled and I do not find these speakers to be dark. They are simply amazing.
Thiel CS 3.7 and Vandersteen 5a, 5a Carbon
I currently have Thiel 3.6's and have enjoyed them very much. I am considering changing to the Vandersteen 5a's or possibly the 5a Carbons. I have read some excellent reviews of the Thiel 3.7's, but have not heard them and it would be difficult for me to do so currently. I would be interested in the opinions of those who are familiar with these speakers. Thanks.