Co-mo makes great bikes (we own 2 and are very happy with both). Without any specifics I would take a $700 price difference between a new and 12 year old bike means the 2009 bike is likely way over priced. The periscope is intended to match an adult captain with a small stoker and to support growth of the stoker over the years. Nothing wrong with that and a good solution for many, but if not needed, there might be some geometry and stiffness compromises (I say that with no knowledge if true or not but only from the perspective that if there were no compromises then all bikes would be built like the periscope.)
I would compare both bikes from the perspectives of the components vintages, replacement options, and upgrade options. Also make sure the bike you get fits you both well. A compromise there is un-fixable (or a great excuse to get a new bike)