I agree with the above comments, and I think that Milo stated the comparison fairly succinctly. I would add that the Thiels will have significantly more midrange and detail than the PSBs. There is another thread comparing PSB and Thiel which you might want to check out, and I posted some additional thoughts on both brands there. I am a Thiel owner, but I have helped several friends pick out speakers, and two of them chose PSB (with several others going the Paradigm route, which you may also want to consider, if you like PSBs). Ultimately, if accuracy and detail are paramount to you, the Thiels are the way to go. However, being a rock fan (and a bass player!), I will say that if you get the CS2.3's, you will most definitely want to get a good sub (REL, or the new DD series from Velodyne come to mind). I recently auditioned a pair of CS2.4's, and while the detail and focus was incredible, I really felt that they were lacking in low end. Same goes for smaller Thiels (although surprisingly, the SCS3 has deeper bass extension than than either the CS1.6 or the CS2.4). My father-in-law has a pair of CS.5's which I helped him pick out, and let me tell you that a pair of .5's with a good sub can sound darn good!
Personally, I went for CS3.6's, because I preferred their more full sound to the more focused sound of the 2.4's. I have one SCS3 for a center, though I am considering picking up two more (or one more, and a MCS1) to round out my HT system.
Hope this helps, Tom.