Yes, I'm responding to my own post, in case anyone else has this question. I talked to my local vermicomposting guru, and she did not recommend using cornstarch-based cups (PLA) in your home compost, because they require a very hot compost in order to break down. She says that even most outdoor compost bins don't achieve the heat needed to breakdown PLA. So - if you are able to, send them to a commercial composting facility.

not entirely true, the problem is the thickness of the cups, plates and cutlery require much longer time periods for breakdown in cooler compost processes ... the 'styrafoam' looking starch products "melt" quickly when wet - I add large quantities of the starch packing peanuts to my bin compost regularly

Bill