I'm another member of the HD2500 fan club. It's so easy to use and (almost) indestructable. I couldn't believe my luck when I picked up an absolutely mint, used once HD2500 for £250.00 a couple of months ago. I was stuck because my original one started playing up. I've still got it and have yet to get it looked at.
I have VDJ8 on a laptop as back up with a HD4500 and it works perfectly for me. I don't really have any intentions of changing my playout set up for quite a while yet.
I didn't go to BPM (I've been once in 10 years) so I don't really have any idea what the new technology is. All I do know is that I am happy with what I have. It works for me and that's what matters.