That's an interesting idea but would present even more problems I think. Not so problematic if you are dealing with a strictly text document but if it contains pictures? Ah, now THAT would cause progress jumps galore.

I must side with the page numbered folk. Like dealing with remaining debt from a loan or amount of time left at work before clocking out, I would rather see actual data telling me something rather than a vague suggestion of how much is left. ("Where did he say that?" "Oh, 'bout a squinch under the halfish point.")