If you should order a new Ovni, which changes would you make?

That's a difficult question! The main cabin is forward of the mast and the bunk is too narrow (my wife complains about it) so I would make sure that the main cabin (wherever it is) has a wide berth.

I gave up the port aft cabin to have more storage space, and now I regret not having that extra cabin.

Apart from that I wouldn't make too many changes as I am quite happy (mine is a 43 - the new 435 is better designed and has a lot more space, and carries the beam further aft). All I can say, that if and when I order another boat it will be an OVNI again (probably the 455 - as my family is growing!).