As far as the different materials, the Clear reels may be more subject to cracking, although the only clear jobo that I have broken is the top part of the dedicated reel in my "Jobo-Triumf 35-16" tank. (that particular tank can be adjusted to do 1 roll of 35 or one roll of 16mm/110 size film.) I do have a couple of the newer style where the center has broken off the tab that locks the two halves together.

One Very Important mechnical difference is that the older style reels can be set for 127 Size films, but the newer ones are only good for 120 or 35mm