I for one, am glad we purchased new only because we were new to boating and didn't know what our preferences were in terms of electronics, general set-up, motors etc. Plus, I didn't know what it took to maintain the boat. Mostly due to this site and lots of trial and error, I feel we've set-up C-Dancer just the way we like to use her.
So I guess what I'm saying is, if you already know how you like your boat set-up and find a good used boat that's nicely set-up for the way you're going to use it, then go for it. I know that if someone bought our boat the way it's currently set-up, I think they'd be real happy. In that way, you can tweak here and there but most of the big ticket items may already be installed.
However, if you think you would replace a lot of the items on the boat, like new motors, new electronics etc., you might want to look into buying new, if it's in your budget.
Peter
C-Dancer