I've midi'd in my Emu Proteus and my Powerbook laptop using Logic Pro sounds with interesting results. Some sampled string sounds for example are very realistic. For live work, I've found it too complicated to use though. Too much set up time and button pushing between songs to get the results I wanted. Most times, the Turbo VL70m was plenty up to the task. If you want to do a more complex live setup, a MFC10 foot switch is a big help. It can send individual program change commands to each tone module with a tap of the foot. There was one in the marketplace you might want to search for.
I've found the best match to the VL70m is a sample based synth. The VL70m synth engine is based on physical modeling. Physical modeling is very expressive and can vary in tonal color with midi control messages sent by the WX5 to match the way a real instrument changes it's sound as you play. The downside to physical modeling is it can be a little thin harmonically. Sampling synths are based on recordings of actual instruments so they are like listening to the real thing. But, they don't respond as well when you want expressiveness. When mixing together the two synth engines, you can get the best of both worlds.