I looked at those two cruises also. You are right the PG goes into drydock during that time frame you listed. I asked TA and she comfirmed it. The sailing in January is the President's cruise. I decided against it as I was worried about the shallow draft on the PG in the open ocean and decided to go with the Mariner cruise next year doing some of the same route Feb 28/09. I just felt more comfortable going with the Mariner as I know she can handle any rough seas better and her cabins are larger for a longer cruise. That is a good price though for the PG as you said. There is speculation that Regent's contract to manage the PG will not be renewed after 2009....so maybe she will be around when you can cruise again and perhaps she won't. It's all yet to be seen.
Pat