My and a couple others actual experience with EZ lube is they leak a percentage of the time. SO with 4 of them the odds are it has leaked. Even when the directions are followed to a tee and all the care in the world is taken, they allow grease to slip past the seals.
The thing is you wont know it has leaked. The brakes still work but may run a bit warmer and they may grab - but they work surprisingly well with grease on them.
So when I read someone saying it has worked fine for years, They don't really know unless they take the drums off - and if your going to do that to check, you may as well grease them by hand.