I feel these are the best strings in the industry for accompanying pop/rock material.
After I bought both libraries and their extended licenses during the promotional special that accompanied the release of Chamber Strings II, I quickly found these to be the best strings for every project I am currently working on, regardless of genre.
For some reason, the articulations just seem to flow more naturally for me than the Solo Strings, Appassionata Strings, or Ensemble Strings. And this is even when sticking to the basic articulations of the standard edition and/or special editions.
What I really like about this library, is that the ensembles are big enough to give smaller arrangements depth, without overpowering anything. And they have character. I feel no need to layer this library with any other strings; it sounds as good and natural to me as layering solo voices.
My Solo Strings II is on its way. I haven't worked as much with the solo strings yet, but am now shifting over to some projects that have far more solom string voicings than emsemble voicings, so look forward to the con sordino option.
I recently sold my Garritan solo strings, not liking the timbre. I'm hoping Sample Modeling will release improved versions at some point, as those might work better for jazz, klezmer, etc.
Before getting Chamber Strings, I had been using Miroslav Philharmonik, finding that it was easier to control articulations and get good phrasing than with the scaled-down versions of the string libraries in Special Edition. I sold Miroslav Philharmonik after delving into VSL's full libraries.
VSL's Chamber Strings is the first string library where I have been successful with minimal effort in octave-doubling parts between different string voicings (e.g. cello-and-violin) and have it blend perfectly. These are very playable libraries, and seem to account for the heft of the bow.
Due to my weak computer, I can go no further than Matrices at this point. Once I upgrade, I can start taking advantage of Presets and make my own. But I only have 764 MB RAM and 800 MHz to play with. Nevertheless, I have made do with mostly the Standard vs. Extended so far.