Not everyone is willing to put fast flite strings on older limbs, but I am. I pad the loops, and have never had a problem. The older Bear td limbs have fairly decent limb tip overlays, I think.
There is one noticeable physical/design difference between the older and newer limbs. The older limbs carry their width further out toward the tip before tapering toward the tips than do the newer limbs.
The newer limbs begin their taper earlier, so they are a bit narrower throughout most of their length. Thus, they're probably a bit physically lighter than the older limbs. However, apparently the extra material in the older limbs compensated for the extra weight so it ended up a wash.
For some reason, the newer limbs seemed a bit quieter to my ear.
Would like to see others do the same type of test I did. Pretty sure they would get the same results, but more data would lend greater credence.