I just set a bunch of personal records on hill segments in Strava with my fixed gear today. Beat some times set on my 2x10 speed bike.

Gear ratio only changes torque, but power in = power out (minus losses, where a FG/SS wins) so if you wanna go somewhere you've gotta make the watts. Now, the multispeed will let you get there with less effort by being able to go slower with a manageable cadence but less effort means longer time. Getting there in less time means more effort. If you need to get places faster with less effort, put your money in better tires, aero bars or a motor other than your legs.