They were GREAT. Much better than any of the snap caps.
I "think" they were primarily for the motor drive, where opening the gate on the cassette reduced the film friction, thus less drag on the motor.
Unfortunately, it appears that Nikon gave up on the Nikon cassettes after the F2. Likely not enough sales to justify making it.
I was bit by the compatibility problem. I have a few F cassettes, but no F, only an F2
For your F3, it appears that you have to use the generic reloadable cassettes.