I have Warn Premiums on my Excursion. They were on it when I bought the truck and I have no idea of their age. They are a little stiff to turn but even in the cold/snow/ice I have been able to do it without too much fighting. So far I have no complaints with them and my truck gets used pretty hard.
Those Yukon hubs looks nice.
Warn premiums should not be hard to turn, unless they are ill-maintained.
Tear them apart, clean, regrease, and reassemble.
Ive run warn premiums on my rigs for ever. Never once had a failure. And none of them have ever been hard to turn.
A bit of grease goes a long way, regardless of how the hubs are built or what material they are built out of.
Factory hubs are on her, but they are manual hubs. Is it possible that they would catch and let go? The noise and vibration is intermittent. Sounds like a shock to the drivetrain when it hits, you hear the grind for a couple seconds, and it goes off. I'm wondering if the x-fer case could be broke and trying to engage. I don't have good old fashioned levers... just a dial on the dash. Gonna have to check out the whole driveline.