On the subject of a 50x13 high gear, I am certainly not a fast rider but for my club rides it isn't high enough. On slight downhills or big rollers I would like a bigger gear, these are the times I can use my power against the climbers.
On my other bike (triple) I have a 52x11, which is a bit much in most situations, but it's nice to be able to stomp down on a big gear when the road tilts down.