I haven’t managed too much time in the train room in the last couple of days but as a followup to my dusty Homasote cutting, I tried cutting out the last few straight pieces for the assorted spur ends using a utility knife and a straight edge. The results were surprisingly easy to obtain and dust(and noise) free. It took about six cuts per depending on blade sharpness.
If you were to use a knife you would have to jigsaw out any plywood layer separately but for a small layout the knife approach would do it. Might be something to consider if one is building in a venue where noise or dust is a problem. Like running your jigsaw in short bursts in your fancy apartment so that fellow tenants cannot triangulate on the noise. Hypothetically speaking, of course.
Here is the stack of pieces I cut which decidedly smoother edges than the jigsaw produced. I think I pushed the drying time on the PVA glue I used to glue down the template.