It has been long held that vertical shots are more pleasing than horizontal ones. I have always wondered if this was because vertical is what magazine publshers want.
I discovered when taking that when taking down my 5000 that I had it set to take verticals virtually all the time. I think partly because the Ikelite rig is so handy UW but I think the main reason is that you can see your image UW and the verticals just look nicer.
Do you find yourselves taking more verticals with digital vs. film?