How is the tea I have only tried several lui an 80's and younger but have not been blown away by any but the two 50's lui an that I have tried were some thing quite special.
The one that I have (from Best Tea House, and probably $80 US or so at the time) is not bad - fairly smooth tasting and a little medicinal, but nothing really special. I am not sure if it's really quite as old as it was said to be.
I have had old liu'an (from around the 20s, I believe) once or twice, and while it was excellent, I wouldn't say that I've had enough experience with older liu'an to really judge or have much of an opinion. Even with liubao, which I've consumed a lot more different examples of, I have a hard time describing, or even recognizing the differences as much as with a tea I'm more familiar with.
I have another one, a New York Chinatown find by a friend -- I think the one I ended up getting was newer than some of the other baskets at the store, because the baskets I have are a bit bitter and unpleasant tasting still. Since it was really inexpensive, I'm not too worried, and will see how it tastes after some more time.
Where did you get the 50s liu'an? My understanding from the articles was that production stopped in the mid-40s, though export continued through the late 40s.