My bike is 46.5 pounds-- sort of an "L" instead of an "SL"-- and I'm fascinated at how minor increases in grade makes a difference in terms of whether, and how long, I can ride without assistance.
On dead flat terrain, I set assistance to zero, and it's hardly any different from ECO, I ride for five miles or more that way. A very slight upward incline is fine for a mile or two if I'm in shape (and I know I don't have a brutal climb ahead.) The bummer is, to get to the Verdugos, I need to ride for four or five miles that are just a few degrees steeper than I can manage with no assistance, and the last mile or two is brutal even in ECO-- and I really need to conserve as much power (in the battery, and in the human) as possible for the climb.
It really might make sense for me to do a CF wheel build for the Motobecane --
@PedalUma, we were considering this for the Marin-- with high-tech low-friction hubs, slightly narrower tires, and maybe even a titanium front fork, CF bars and seatpost, hollow cranks-- the whole weight weenie package. Could I drop four more pounds, decrease rolling resistance even further, ride without assistance longer, and get significantly more range? It would really help give me better access to steeper and more interesting terrain.
Of course, I have to have super lightweight clothing, tool, and water options as well. (That sounded senseless, I cannot decrease the weight of water! I do have a lightweight sling option for a small plastic water bottle.)