Originally Posted by
pdlamb
Back to the original question: yes, it'll make a difference on steep hills (>12%, perhaps), or if you're touring with a load. In other words, if you run out of gears with the setup you've got, that change will give you about 1.5 extra low gears, and that's often significant.
I concur with pdlamb - If you do loaded touring in mountains, you will appreciate the lower granny gear.