sleeved vs ball-bearimg fans

[Wigwam]

i understand that thermaltake are using ball-bearing panaflo fans on the silent boost as panasonic couldnt make enough sleeved ones to keep up with demand.
So what is the advantage of a sleeved fan over a ball-bearing one?

 

[0roo0roo]

quieter.
ball = longer life

 

[WobbleWobble]

Sleeve bearing fans are quieter and stay quiet till they die, then they're dead quiet .
Ball bearing fans get louder overtime, but they last longer than sleeve bearing fans.

I'm not entirely sure how Hydrowave works, but with my experiences with the SilentBoost the Hydrowave one was noticably quieter than the ball-bearing ones. I tested both, but at different times, unknowingly one was a ball bearing model. It seemed like Hydrowave is quite a bit quieter.

 

[Cerb]

Sleeve: lower life, quiet until death.
Ball: longer life, louder.
Fluid: lower noise, longer life than normal ball.
AFAIK, there are no sleeve bearing Panaflo fans.