I could tell you stories of beating the needles out of rockers at 8500 and what the cost is.
A bushed ductile iron rocker or even the Crane rockers are better than the HS crap they sold me.
As for T&D I only use those with bushings in them. Period. If they won't do the bushings (they will but they ***** and moan about it) then I find something else.
Again, aluminum is used because it's cheap to buy and manufacture. Needle bearings were used by the Chevy guys because that's all they had.
Many, many rocker manufacturers now offer steel rockers with bushings. Look at the latest Hemi rockers out there. Steel with bushings. Guys ain't spending $7500.00 on rockers for bragging rights.