As is the case with most of technical bicycling articles I read, I can't understand a word of that Sheldon Brown gear ratio gobbledeygook!

Personally, I don't think you need to get so technical. I ride to work everyday with my left (front) shifter on "2" and my right (rear) between "4" and "7." Recently, I did an overnight trip that took in all kinds of terrain, from flat streets to a hell of a climb over a suspension bridge, and from smooth pavement to very rough gravel. Over the course of about 50 miles each way, I never used more than seven gears, and for the most part, I stayed within the same four I use on my commute.

I'd love to get myself a seven-speed, especially one with an internal hub so I can stop worrying about derrailleur adjustments and maintenance. I don't know the type of gears you have, but enjoy them and, for the kind of riding you're doing, don't worry about needing any more than seven!