er i dunno about the gearing, its hard to say, what gear do you find most comfortable on your current bike, use that :) i would go for a cyclocross bike if you want fast commuting and dont mind riding drops, there a bit stronger than road frames and have geometery which allows you to go offroad "now and again" but you dont sacrifice wieght for strength like you do with the SF1 (im saying its probably heavy :) )
er i dunno about the gearing, its hard to say, what gear do you find most comfortable on your current bike, use that :) i would go for a cyclocross bike if you want fast commuting and dont mind riding drops, there a bit stronger than road frames and have geometery which allows you to go offroad "now and again" but you dont sacrifice wieght for strength like you do with the SF1 (im saying its probably heavy :) )