Fixed gears do not create some sort of magical extra momentum. Its a myth that defies basic physical laws. Many of you need a physics class.

If you can pedal a freewheeled bike, and keep the pawls engaged (virtually anyone who can ride a bike does this), it makes not a bit of difference whether you are climbing a fixed gear or a SS. If your pedalling is so sloppy that you can't smoothly pedal a freewheeled bike, then you need to work on more than just your climbing skills.