[arrivederci]

David, I completely understand your point about surge brakes possibly dragging on a long downhill. This is exactly the point that the Trailex salesperson was making. I've also heard that if the trailer begins to oscillate (swaying back and forth a little), its helpful to be able to tap the trailer brakes to stabilize it. There's no way to do that with surge brakes but with electric brakes, its no sweat.

These days, most surge brakes are "free-backing"...which means that they're engineered to not engage when the wheels are turning backwards.

They are less prone to failure than electric brakes. There's much less to corrode/troubleshoot, and the emergency brakeaway doesn't require a battery. Apparently, the corrosion is a serious issue in wet/coastal areas (due to salt, etc). I suppose that surge brakes need to have their fluid replaced every once in a while, and possibly their lines bled (since they are hydraulically acutated).