Mattias Westlund did an amazing job putting together the Sonatina Symphonic Orchestra for SFZ. While lightly sampled, the whole thing hangs together amazingly well given the wide variety of sources. This is thanks to layering, clever use of IR to place instruments in artificial space and other things I don't understand.
I have Kontakted the orchestra and added Big Bob's WIPs scripts. This should let you use legato, vibrato and breath controllers. The main problem is that with so few samples, you tend to get the 'shotgun' effect on solo instruments and there aren't many, if any, articulations. However for sections and background it works very nicely. Many of the multi instrument patches have a staccato articulation and most strings have pizzicato as well.
"SSO is a free (as in speech, and beer) library released under the
Commons Sampling Plus 1.0 license."