Bushing Caps for Control Arms

[Three504spd]

Schurkey, that's what I did, I ordered from Rock Auto, cheap enough at $6 a set!! In line with this conversation, what are the drawbacks, concerns or problems with running both Rubber and Polyurethane bushings? Ex. Upper arms rubber, Lower Poly?
I will not be doing this myself but Im curious what the ramifications might be.

 

[Schurkey]

Whatever arms get rubber bushings will have to have the through-bolts torqued with the vehicle at normal ride height.