This is a very simple feature request! Next to (or maybe below) the gearscore, you should have the average iLvl for the gear equipped in that set. I like to use a mix of gearscore and iLvl to get a good approximation of somebody's gear.
On an unrelated note, what's up with the "Avatar" on the gearscore page just being a shadow? I could have sworn I saw it working before, but it's not any more. Fix it? =D
Just had another idea. When you mouseover the green/yellow/red bar, it should say the gearscore that matches your mouse position. It's hard to figure out what gearscore it's suggesting for certain raids when the only score you can see is your own.
If not the mouseover thing, then maybe small numbers under the bar saying 4k, 4.1k, 4.2k, etc