At around 4-5k my CCS started making an intermittent honking noise and I couldn't figure it out. After a while I figured it was the rear brakes. Pads were down to mostly metal but front brakes were only 50% worn. At about 7-8k fronts are still ok. I think the rear hub motor does the extra wear.
I use it for commuting so I might not be as aggressive on the pads as someone who uses it for exercise, or leisure, but either way I think you both have a while to go.
***CCS odometer resets roughly every 1500 miles so these are rough estimates. It's known issue.
