O''''Day 40 live aboard/blue water
I have not owned nor sailed an O''Day 40, but I have researched them and inspected one. I thought I would reply as no one else has as yet.
Practical Sailor implies that the boats are built fairly well but definately not bluewater. Most other reviews seem to re-state that position and label the boats as costal cruisers only. There were several things that I found not to my liking when I looked at one (in excellent shape by the way). My gripes came to a focus when, in the aft cabin (not a true cabin really), I looked up to see that the cockpit above appeared to be nothing more than a thin liner screwed to the hull.
The boat could cerainly be a livaboard (I had a friend who lived on a Pearson Triton 28). With its light, questionable design/construction details and balsa cored hull (I am in the camp against cored hulls for offshore and distance cruising), I think the authors who considered it a coastal cruiser were probably correct.
I do not mean to disparage the boat, PS went on to say it was a cut above Hunters. I just hope this limited view is somewhat helpful.