The real problem is that most of my commute is so flat that even the middle ring is too low to be useful. I think I could ride this thing up the side of a building in the low gear.

I'm not worried about top end (gravity's doing all the work any time I spin out my top gear). I just don't want to have to shift onto the big chainring as soon as I start moving.

Besides, I'm using an old 8-speed XTR cassette. It'll probably never wear out.