Last October we stayed at POFQ and would sometimes take the boat up to POR. If you happen to catch the boat when it's coming in, then I think you could save some time over walking there. But if you just missed it, it could be a while before there's another one. As the other poster said, they don't run as frequently during the day as they do at night.
We did probably take the boat 3 - 4 times from FQ to POR to eat, then back again.