Interesting view. When we were looking for a boat I liked portholes just because of the older style look. We saw lots of boats and liked boats with all sorts of window styles. We ended up getting a boat with 10 x 15" portholes - I was wary about the light, but now having got the boat it really isn't a problem and not as dark as I envisaged and am glad with the choice. We personally find there are more benefits than disadvantages:
More secure (cant smash and climb through it)
Cooler in Summer and Warmer in winter
Little condensation
Easy and inexpensive to replace glass (5 secs), we carry 2 x spare windows
Easy to take out entirely for really hot days or for washing windows!
Don't have to draw curtains when mooring as passers by can't really see in unless they come right up close.
Much more cosy!
Just thought this might be useful??!!