I owned Thiel 2.3s for a no. of years and have heard the higher-end Vandersteen models on a no. of occasions (sometime after purchase of my Thiels). My next speakers will be Vandersteen Quatro CT or Treo CT (although I wish to check out the Golden Ear Triton models for a possible- and substantially more affordable- alternative, and see if they live up to their press).
Re. Thiels, my model had some problems with edgy high-end (primarily with digital rather than analogue presentation (on my Rega planar 3 and then an older Linn LP12 with benz micro cart), but had all of the positive attributes of the Thiels as well, and were eventually tamed by component isolation, judicious cable selection, and dampening an overly-bright listening room that I had. I used them with an Ayre cd player and Ayre electronics, excellent their own right, but not the absolutely best match for the 2.3s.
FWIW, I also heard the Thiel 2.4s sometime after I'd bought the 2.3's in a setup nearly identical to mine, and were definitely superior overall and without the edginess. Also, the folks with the (now-defunct) Audio Perfectionist journal, who had impeccable taste in gear and setup, were big fans of the Thiel line (though bigger fans of Vandersteen).
The Thiel are fabulous speakers, but a bit more system-sensitive than the Vandersteens, I'd say. While I've come to prefer the Vandersteen sound, it's easy to understand how many people would love their Thiels.
