Thanks John....How would you have done sailing the 31 as your first boat? How long do you imagine the process to singlehanding her would have taken you -- a full season of active sailing / planning / practicing -- or more? ...
I think with your background, and a little bit of help/lessons from an experienced sailor, you'll be fine in a boat this size. As another poster mentioned, a mid-size cruising boat can in some ways be easier to handle than a smaller or pocket cruiser, especially out in heavier conditions.
The trickiest part to get used to will be docking manouvers, but if you're on a mooring or the anchor most of the time it will be less of an issue. Wait for a calm day and then take some time to practice docking, it will improve your skills and boost your confidence.
....The 31 is an odder duck. It has the head to port at the bottom of the companionway. Some CD'er really like it as a combo head / wet locker, but it is fairly unique (though I guess the PSC Dana has an equivellent set-up). The upshot on the 31 is they are limited in number and fairly high in demand so either the 33 or 330 will likely be cheaper.
I prefer the aft head arrangement. Especially for short-handed sailing, it makes it more convenient to take a quick duck below. It's also handy for peeling off the wet foul-weather gear. The Dana is configured like that, as is our larger PSC 31. Speaking of the Dana, you might look at a few since they're in the same price range.
By the way, what kind of tankage are you talking about in those CD models being discussed?