If dRs are SO efficient ....
Then why does every LHT rider complain they ride like SLUGS ???
Then why do all tour guys all think they need a 20 GI ???
Then why does weight weenie matter SO much ???

All I can compare is the bikes I have used, none were less than 40 lbs as used.
dRs are LESS efficient in any gear is what I concluded after riding 2800 miles with my XL-RD5w and XL dyno front hub.
They accelerate faster mostly because of WEIGHT difference, they certainly are less aerodynamic. and pathetic when the chain gets dirty in the real world.

My Fastest ever speed = SA on the first try, 44.63 mph wizzout from standing start on a bit over 1/4 mi hill.
This spring it will go up to 50 easily, when it is on my custom roadster and use a 48/17T.
Best at hill climbing = SA, with un-low of 43.5 GIs Less strain, more speed for same effort, even on 20% heavier bike.
I went farther with the SA than I ever thought to go with dRs, Zero worries.