I have done “only” about 1000km as my typical trip is a 5-7 mile leg with a climb of 800-1500 ft and then back. No long runs. The tracks are pretty rough with a lot of loose scree. This uses about 60% battery and I am not a lightweight.
It’s a Yamaha. Bought in 2015. Not a + bike. 500w battery.
The only mod is I had a smaller chain ring fitted to give me lower ratios to help with heavily laden climbs (plus I am mid 60s).
This was my first Ebike and I did not know what to expect, but I cannot think of anything else I have bought that has so exceeded my expectations. A friend bought the same bike at the same time. He has done about 2000km with no problems.