Radius arm bushes? I'm assuming thats what we are talking about, and if so, anything other than genuine rubber Nissan items do reduce flex, and wear faster IMO
Rubber work better and last longer! If you fitt unrethane in the control arms they will not last very long. I fitted some and they came out in pieces after one competition! ie they split in half!
If it was me, I'd just fit factory (style) rubber bushes in everything. Some of the aftermarket ones seem to be pretty good but factory ones just aren't very dear anyway. eg about $35 each for the last lot I got.
Nissan Terrano coilovers, turboed VH45, Safari axles, and some other stuff.