Me.
Just did a complete overhaul of my bb. Upgraded the octalink bb, and thought I'd dump the lx front mech for an xtr. Got home, stripped the bike down, threw out the rubbish, etc. Today, I rebuild the bb, fit the xtr and route a new teflon-coated cable. Neat. Connect the cable to the xtr but for some reason no matter what I do I can't get the front mech to shift up and down. Then it dawns on me. My original lx mech was a bottom pull (cable routed under the bb). The new xtr is a top-pull. I don't have anyway of fitting a top pull on my frame. Result. Yup! Strip it down and refit the original lx. Getting the xtr back for refund/swap-out is impossible now. I travelled into London to get it, and I mentioned the rubbish, right? Rushed outside, but it had all been taken, box...and receipt which I put in the box. Now I'm running on the very lx I wanted to avoid, and am stuck with a brand new xtr I can't use. Clever, eh?
Maybe my wife's bike is a top-pull.