the champion edition plastic was from a polymer-based blend if i remember correctly while the champion stuff now is from a nylon-based blend (which contrasts to discraft's vinyl-based blend for z plastic).
from what i have seen between the two plastics, they are of similar durability, but the CE plastic had a more gradual break in period vs. the newer C plastic which tends to have a rather quick initial break in that yields a fairly substantial flight change early and then the flight changes are more gradual after that.
it's hard to compare the flight a lot since most of the early CE discs involved the L mold variant (eagle, teebird, firebird) but the CE discs also varied a lot run by run (the 4th run flew like a slightly broken in 1st run, but the 2nd and 3rd runs were way different) and didn't really mimic the DX versions. C discs tend to more closely resemble the DX versions but are quite a bit more overstable. i.e. if a new DX teebird is a 7/5/0/1, a new C teebird is more like 8/3/0.5/1.5 until it is significantly broken in, but a CE teebird TL was more like 7/5/-1/1.5 via innova's ratings system. the original CE blends had horrible yields (often in the range of 70% of the discs beind X-outs or regrind) and they experimented a lot. later CE blends more closely resembled the newer C blends but the C discs are still a bit more overstable.
the first 6 runs of CE plastic were also much stiffer than the C plastic now, although around run 7 (run 6 being the first transparent runs since some of the freak ones from runs 1 and 2), they began running the transparent, gummy plastic.
also as a general trend, for both CE and C, the more opaque versions of the discs will be less overstable than those that are completely translucent/transparent as the clearer they are, the more "pure" % of the durable plastic and less weight agent and other plastic blends they sometimes use to reduce some overstability and more closely resemble DX versions in flight while still being very durable.
hope this answers your question.