Here's my experience with them. I bought a used 2010 3 axle toy hauler with EZ Lube hubs. The braking was not to good so I thought it was time to up grade my controller so I bought a P3 controller and brakes were the same. I started taking the brakes apart and found two brakes that the adjuster springs had broke and the springs and adjusters were in the bottom of the drums. Three seals leaking bad enough to grease soak the shoes and one seal completely pushed out of the hub.
My advise to people buying used is first thing remove hubs inspect brakes and repack bearing and then you can elect to use the EZ Lube axles to lube bearing or remove and repack them on a normal maintenance cycle.
With this trailer being the first one with EZ Lube for me I will run it for a year and then remove hubs and inspect, If all looks good I will probably Lube them once a year thru the zerk and then remove and inspect every 3 years.
After I packed the bearing and put all back together I greased them thru the zerks until grease came out of the outside bearings for a test to see if it bypassed the seal. I'll have to get a couple new seals to have on hand and then after putting on about 500 miles I will pull a couple hubs and check for signs of leakage.
Oh by the way, did I mention I "HATE" packing bearing..........