Personally, I've always marveled at the idea of why a 24 valve DOESN'T have more rocker failures than they do.
A roller tip probably isn't much, if any, better than the ball/socket tip design they already run, Lord knows they still wear the valve guides out with either design.
The saving grace is that the 24 valve uses so much less (stock) spring pressure on the valves than most engines out there, which probably keeps the rocker failures way down, but I still see a lot of galled fulcrum and shafts from stone stockers.
I throw a LOT of damaged (usually galled) stock rocker arms away.
Oh, for the record, I'd NEVER run a needled/caged bearing on the fulcrum of ANY rocker, it's just begging for trouble.
Bronze works just fine, IMO.
Mark.