I love my surge brakes and would go that route again in a heartbeat.
I have a triple axle with surge brakes on two axles. Drums with free-backing cams in them.
Only gripe at all is the thunk when taking back off from a stoplight. I just ease out on it first. Also happens after braking on a downhill.
What I like so much is that the hyd surge setup matches braking force to the need. However much braking you need up to the point of lockup if necessary. This is the case either loaded or unloaded.
Also like the fact that if the boat became loose from the truck that the brakes would engage.
I've driven car hauler traliers wit5h electric brakes and here's what I don't like about them:
I've used a 2-stage brake box that gives two stages of braking (plus manual override). With the trailer loaded you gotta jack up the voltage setting. With the trailer unloaded, you end up locking the wheels and being generally hard on the tires unless you back way off the voltage setting.
I also don't know how I feel dunking an electric setup (I'm sure they make some for water use, but am leery of it).