Doug-
Yes, you can operate in conventional mode with the ZW-L. All of the 'normal' Proto2/3 functions (couplers, horn, bell, special freight/passenger announcements) can be triggered via the correct bell/whistle button combinations, and you will have speed control. Without DCS you will lose the ability to operate multiple engines independently on the same track, as well as some of the more advanced Proto2/3 feature such as on demand chatter sequences, and the Proto-Doppler.
-John