I bought the 2509 reels and tank when they were new. I had lots of trouble with uneven development with flow marks from the reels, and quit using them almost immediately because the negatives were useless. The 2509N reels were introduced later with some snap in baffles designed to break up the flow patterns for more even development. I haven't used those. Also, Jobo changed their recommended procedures for pre-soak and rotational speed a few years after the 2509 reels were introduced.

The 3006 and 3010 tanks were introduced later, advertized as giving professional results compared to the 2509(N) reels. Given all the reports I've read from users over the years, along with my own experience, I'd say the 3000 series tanks are highly likely to be more consistent in giving even development.