While I'll always prefer the Classic SXS on esthetic terms, the O/U is a bit easier for me to tame with a variety of loads. You have called it right on target about both quirky types of doubles.

I was making generalizations about the basic characteristics...wouldn't turn down either configuration!

The biggest disadvantage to the O/U is it gets top heavy as it gets bigger, and is a real bitch to get a shell chambered into that bottom chamber when running...at or away!! They have to be opened up sooo darned far, unlike a SXS. A 375 is about as big as I think is practicle in an O/U.