I have to report that I was doing several tracks using another library's recorders, which were not bad, but when I switched to the new VSL recorders it blew me away. Suddenly, the merely passable line was a fabulous espressivo musical sound. The wonderful playing on this is truly inspiring, and I had to add more recorder parts as a result!
The soprano has an amazing high register, the alto and tenor a warm rich sound, and the bass is a deep mysterious timbre I've never heard before, reminding me of the great VSL bass flute. These can be used not only in baroque or medieval period sound, but also for really evocative film scoring. And the crossfading from vibrato to non vibrato, which Herb suggested to me, is absolutely perfect and adds an expressive touch. This is another great example of the artistic sound that VSL has created over and over again.