The experience I've had in this forum is that it's the riders in flatter areas who get the best life and performance from Li-ions.
Unfortunately the waters are muddied by people thinking the steepest hills in their area are steep, when they are often mere slight slopes to many of us, so the subjective reports are simply not reliable, few acknowledging that they ride in a very easy area.
I've had members referring to even a gentle 7% slope as a "very steep hill", though it's only a third of the steepness that many of us climb, and 10% is commonly thought of as steep.
The other factor is length of hill with Li-ions, since they tire under sustained heavy discharge. A short hill of 10% might be well within a powerful bike's capability, but a lesser 7% hill going on for two miles can tire the battery cells so much that they drop to safety cut-out point
It's the riders who regularly climb hills between 12% and 22%, or hills lasting for miles who give their batteries the roughest time, and accordingly get the shortest life. I have both type of hills and the unenviable record of 3 early Li-ions failing in months, two of them with under 60 charges.
However, that wouldn't happen on the Panasonic motor unit battery, since it's power management doesn't permit abuse, rationing the battery output to keep it well within it's capabilities at all times. The only hub motors approaching that level of sophistication are the BionX and Sparta Ion, both direct drive types.
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