Some people like them, some people feel the K and E series is an improvement due to their sensitivity and power handling combined. I would never speak ill of the D series speakers, but they are more fragile than the K and E series for loud jamming and gigging, especially at there age. I would love a pair for a vintage amp at the house.... I guess it depends on what you are buying them for, but yes with the right tricks of the hand you will sound like Jerry all day long. I prefer the E series speakers despite the weight, The K series are a little too bright sometimes for me. From what I read around here you can get a new Weber speaker that clones the D series tone pretty well.
I have purchased all my JBL's at or under 100 bucks on the bay, but you have to be patient. These sound like a deal though considering the D series go for much more than the K and E. I wouldn't have remorse picking them up at that price. Good Luck man, Sounds like you got a good find.