Carrier Bearing Drop

Hey seen some posts concerning this, but when would you need to install a driveshaft carrier bearing drop?

Like this:

 

Aren't axle shims for that? Can you still get vibrations if you get the axle shims when you lift? Is it a good idea to just go ahead and get the bearing drop as a precaution or are there risks associated with it?

 

I would go with the BEEFED one its a lot better then that one. I'm running it and it helps a lot.

http://www.streetacos.com/

 

Would I even get vibes from the driveshaft if I'm only lifting by 2inches in the rear?

 

Alright, thanks!! Just trying to get everything right the first time and on a broke college student's budget