I've polyurethaned some maple trim with a water based finish (no color, just poly). It didn't quite get the slightly rich yellow sheen I'd hoped for to match some other maple nearby, which oil based finish would have given me. I vaguely remember that you can either put oil based over water based, or vice versa..... Of course now I can't remember which.
Has anyone tried this? I'd like to "richen up" the trim, and sanding it down to try it all again is out of the question. I do have some scraps I could try it on, but I figured I'd ask first.