I have the two you show above, too. Pretty much the same.
I like to think the Chorus is different, but that just makes me feel better.
I also have both in the 7-sp pre-Ergo version. Of course, they're not labeled, so I wouldn't know.
The Chorus came with a Chorus group, and the prev owner had no problems shifting.
After I put it on a bike, the owner complained that the shifting was off.
The insert was supposed to work with Athena, not Chorus. Somehow, it worked fine for a trusted colleage before.
So, I bought the Athena RD, or at least that's what the seller said. It doesn't work any better on the same insert.
I think it was owner misadjustment, because it worked fine when I had it and test-rode it. Go figure.
This experience probably set back my conversion to Campy about a year.
Now, I just don't give a ----, I use Campy stuff, 8-sp and up, and call it a day.
You shouldn't change the Frisbee.
1985 Raleigh Racing USA - Coleman's Competition
1984/85 Klein Performance
1988 Centurion Dave Scott Ironman Master
1989 Centurion Dave Scott Ironman Expert
1989 Centurion Carbon R