I haven't tried this with VSL before, but the playback with microtones can be achieved with either VST2 or VST3. In VST2 the method used is almost not implemented by any vendors - I believe NotePerformer is the only exception that supports it.
For VST3, the method for playback of microtones should be more broadly supported by any VST3 instrument that supports note expression for detuning. However, not all VST3 plugins will do this. So the plugin being VST3 makes it more likely that it will playback microtones, but it isn't a guarantee by itself.