I have had 2 Dashes. Both had troublesome Shimano brakes. I replaced the Shimanos on my 2014 with Sram BB7 brakes and problem solved.
Sounds familiar. I got my 2016 E3 Dash a month ago and have loved it, almost to death it turns out. I've put 800 miles on it and strained my relationship with my dealer/friend. Here's what happened.
The front brake started leaking fluid after 2 weeks. Using the back brake more often and braking from higher ebike speeds caused the back brake pads to wear completely away in 800 miles. I took the bike in for warranty brake replacement because the front brake leaked fluid and they couldn't bleed and recharge it because the reservoir cap was stripped. The dealer said Shimano won't replace just one brake, only both of them, under warranty. But he didn't think about labor. Running the back brake cables required that they remove the motor and they ran up 5 hours of labor, which Shimano doesn't cover. And I didn't even want the back brake replaced, only the pads, which I could have done myself.
Anyway, any idea what happened with my back brakes? How many miles should I get from brake pads? I know it depends on many factors, but wondered if you thought 800 miles was way too low or not. I think my case was a perfect storm of riding with no front brake plus lots of miles in my honeymoon phase...
Going forward, I'm going to check the pads every few hundred miles, and I'll upgrade them if I have any further problems.
PS
Also getting a new battery and headlight under warranty. I'm only getting 15 miles, which is on the low end of normal. But I'm also getting lots of flashing-red on the charger, indicating the battery or charger is too hot. This has led to no charge when I need it: if I plug it in and don't notice the flashing-red, it doesn't start charging>
The headlight issue is this. It has several detent clicks to adjust the throw of the beam. In the bottom click, the light turns off, which Izip support hadn't ever heard of. It wouldn't be a problem but sometimes the light clicks off when going over a bump on dark trails. So, they agreed to swap it out.
Glad izip has good support! I look forward to a few years from now when ebikes are as reliably as my 1998 Schwinn Mesa.
BTW, I wonder when Shimano, etc will update their warranties for the ebike era. Conventional components can't take the higher stopping speeds, etc. I expect the warranties to become more car-like, "2 years or 1000 miles, whichever comes first" and for the components to have an 'ebike' rating, and the warranty will be voided if you use non-ebike-rated components on your ebike.