I am considering buying the Porter Cable 4 1/2" trim saw with
appropriate blade for use on cutting large sheets of plastic. My
impression from this newsgroup is that the larger 15 amp worm gears are
used for framing and not finishing.

I am curious if anyone has experience with this tool for cutting upto
3/8" hard stock.

I would highly recomend this PC saw. I have used and sold this saw to
cut plastic. It will
do a good job and give you years of trouble free use.
Mike