At 45mph, or long before, I'm not pedaling anymore but merely taking advantage of gravity on the real steep, straight stuff. Gearing becomes inconsequential, for me at least.

What I mean about getting dropped is in the ~30mph range where spinning out is a real factor in keeping up. 5-10 miles of, say 6% grade will make you curse that compact crank pared with a 12T cog if the rest of the group ride in 53-11.

But these musings of mine are esoteric circumstances of little real life value, and only hurts the ego should they arise, so all's good.