I've found that MEK or Acetone will remove the poly glues easily when they're wet. I too have switched to poly glue in a lot of cases where I used epoxy before. It's simpler and strong enough for most things. I still use epoxy for firewalls, landing gear and some laminating tasks, but I also use poly for laminating.

The reason I sometimes use epoxy instead of poly is because it's neater. For example, when gluing a doubler in place, I don't want to mess around with sanding away the part that foams out, so I use epoxy.

When I laminate plywood to make a former, I always make it oversize and then cut to shape. Poly works great there because I don't have to worry about the excess.