The only thing about this "pre-Rola" stuff is that it gives the impression that Rola-labeled Celestions are inferior in some way to the older ones. I don't think this is necessarily true, I've had "post-Rola" Celestions that sound great. It's just a way to differentiate the different eras of Celestions, and not an indication of quality. The main thing about the older Celestions is that they are OLDER, and speakers change in magnetic strength over time, which results in a change in tone.
Al