The only "free speed" with electronic shifting would be for short/technical courses where being able to shift from the basebar provides advantages over shifting from the extensions alone (as on mechanical shifting). I.E. you are very frequently cornering, and needing to shift coming out of the corner while still on the basebar. For long course, which generally has few corners and rarely technical, there is no advantage to electronic over mechanical from a speed point of view.

There is, however, much speed to be gained from the extra items in option A.

Electronic shifting is cool. It is also has a convenience factor; doesn't come out of adjustment, no cables/housing to wear/replace, easier to travel with when having to remove derailleurs or loosen cables. But it you want speed, spend your money elsewhere.

P.S. for someone your height, I cannot imagine that a 51cm frame is a good fit. Maybe, because you are flexible, you are trying to use the smaller frame to get less stack? Would a different manufacturer be a better fit? Just a word of warning, it doesn't sound right....

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2015 USAT Long Course National Champion (M50-54)