I originally thought the "ii" series were just outside cosmetic changes to the originals. I was wrong.
What I've found in forums like this is that JBL was sued by Bose over the port design of their speakers because they were just TOO similar: which I'm sure Bose has a patent on.
Anyway, also check the diameter of the tweeters. Alot of the original N(orthridge)-Series speakers have 3/4" tweeters like my original NSP1 package's N-Center and N-24s. If the ii's have 1" diameter tweeters like the S(tudio)-Series and newer N-Series ii's then yes the $100 extra is justified. Also I personally think they look better but I've never heard the new ones.
If the ii tweeters are not bigger and/or the wattage handling is not higher then no: the originals are a better value.