Well, I try to chime in over there when I can...but they are slow.
I did get a M203 for my WS. Here's a couple shots of it.
Works really well and had some really good results with it a couple weeks ago. You need to modify the shell some if you want decent range out of the nerfs though. At 700 psi I can get 245 fps out of it and about 130 yards in range easily.