Cons:
1. My VL UP Genset has an annoying background buzz in the sound system. When running the system at full volume it is drowned out, but if the engine is sitting on a powered track without being addressed the background noise is clearly heard. I think that this was an issue with some early Legacy (modular boards) engines. But not everyone with a VL Genset reported having this problem.
2. Smoke volume out of the stacks was slightly disappointing in my case at least compared with the VL GE Evo and various videos I have seen. But the cycling of the smoke on and off in both engines, and the triggering of 1, 2 or 3 stacks in the Genset, is a great feature. Probably I need to play around with the Genset smoke settings more than I have.
P.S. I would never open mine up to fiddle with the smoke units - there is just too much crammed inside the shell and in fact I never got the battery to fit in the place designated for it!