We found we had to sleep like we were sleeping in a traditional V berth. Since the foot of the bed tapers, we found if we tried to sleep like we were on a rectangular bed, our feet would hang off of the tapered edge.
If we each follow- the edge, our bodies form a V with our feet close and our heads further apart. The made the bed much more doable. I'm only 5' 9", but have a friend who's a bit over 6 feet who didn't mention there being an issue.
Keeping in mind that the master on the 390 (my friends boat) and the 400 are already larger slightly larger than the 350.