geared is faster! No matter if it is flat or hilly!!!
sorry....

You can accelerate faster off the line and reach a higher speed because you can change the ratio of your gears with an easy flip of your gear lever!!!

People attribute SS with faster (or good for training to ride faster) because you can't down shift, forcing you to power up hills in your high gear. This is nice (and good because I like to power my way up hills, luckily Tokyo doesn't have too many!)

But when it comes to flats, I find that I have a lot more torque to give, I don't want to spin my legs at crazy high speeds, I want to use that crazy raw power to go crazy fast. I could go higher ratios, but i am at 48/16 now, which many consider quite high for road use, also it will make accelerating off the line slower.