I have one, the speaker is not enclosed, it can be improved... it's ok. It sounds a lot better if you enclose the back of the speaker, but of course that makes it more of a challenge due to space.
I went with a single board solution, track power DCC which makes it a lot easier. Have not converted the smoke unit yet, I think I may give up on the mechanical puffer. Funny the puffing smoke is not listed, just "operating smoke".
For those who don't know, there's actually a mechanical mechanism with a piston to make it puff... but it looks and works crummy.