[dcb]

2 lbs is not huge when compared to 200 lbs of rider and bike and crap, it is 1%. Having gears so you can pedal at whatever pace is comfortable for you is huge by comparison.

The extra drag of derailleurs is not a big deal, any transmission is going to introduce some of that, and the chain derailleur is particularly efficient since you do not leave every gear meshed at once and spinning, just a couple idlers.

I always prefer my old le-tour for the tall high pressure tires seem to roll the easiest on pavement. Even in the snow, I have to plow less snow with the skinny tires, they just cut through to the pavement.

I had a suspension bike, didn't like how pedaling compressed the suspension and soaked up energy, but I did like how you didn't even have to hop to clear a curb, that's a more delicate maneuver on a le tour.