I keep seeing posts for O'Days on this site and every time I read them, they are positive. I haven't had all that much experience with them, and definitely none recently, but what little experience I had was not at all positive. In fact, my boyfriend and I used to call them Oy Vays.
We worked on a brand new 26' O'Day for a couple and they also owned a 25' Dufour that was several years (decades?) old. There was no comparison. The O'Day was total pain in the a*s to sail. And the Dufour was sweet. We were given the option to sail either and always chose the older, uglier Dufour.
The O'Day just seemed really cheaply constructed and the running rigging was not intuitive at all. In fact, I could say honestly that I hated that boat. The word 'dog' springs to mind when I think of it.
It seemed like it was built for people with little knowledge of sailing or boat construction. It looked great on the surface, but once you actually sailied it or took a closer look, it revealed its true nature -- ill-conceived and cheap. Maybe that has changed -- after all, this was many years ago (late 80's).
So, I'd like to know if O'Days are different now. Maybe they really polished up their act and are now constructing well-built, smartly rigged boats. If so, then great. If not, you couldn't pay me to take one on. I'd keep looking and ask someone with lots of experience to look with you.
If you were talking about a day sailor, I wouldn't worry so much, but a new 40 footer has got to be a chunk of change and worth considerable research. Good luck and hope I'm wrong about O'Days.