I'm not sure what to tell you about the arm band. I end up holding mine more often than not when I run. Its comfortable enough on my arm, but I like being able to see the display. Plus, on longer runs where I sweat a lot it would tend to fog up on the clear window.
I see nike now has an arm band with a clear screen, which was my main complaint with their original nano holder.
This is similar to what I use for water on long runs, although mine has 2-10oz flasks instead of a 10 oz and a 5 oz one. It has worked really well. Once you get into a rhythm you don't even notice that its there.