The warranty is not just about the $12 V brake. If something does happen, then they can void it for everything on the bike and frame.
Where we ride is pretty flat and we only go up to about 16 MPH max so with the experience I have, I think we should be fine. The wife does not want us to go too fast. I was talking to her about replacing the stock 26x2.0 tires with narrower ones and she did not want me to do that.
The "traditional" ferrule I add did firm up the brakes. I guess it must have gone into that spring a bit so effectively I have a shorter spring in it now for the firmer brakes.