I've owned a 308 and a 408. I think the latter has a faster retrieve or is a newer version of the 308. But I lost the 308 and other tackle in a move during my divorce, and gave my son the 408. Going by memory on the faster retrieve
I bought the 308 used from another airman during my first year in the USAF in the 1960's, and it caught a lot of fish. Not suited for heavy duty, but I never lost anything I managed to catch on it.
MY only current spinning reel is a very smooth Shimano, but I have fond memories of the Mitchell 308 and 408.
I think the 300-series are/were the best basic spinning reels of their times, and still hardly obsolete. Of course, even a bamboo pole and a string with a minnow or jig aren't really obsolete...just very limited in where they can be used. But the 300-series can certainly be called "classic" in the full sense of the word.