So I got my new 1500 tank system and and reels yesterday. Took a quick look this morning and those older reels do fit in the new tank and would definitely work well for inversion processing.
However... I intend to do rotary processing and the newer reels have some small tabs on the inside that seem to grip the core whereas the older ones don't. The older style reels spin very easily on the core so I think doing rotary processing there would be a risk of uneven development. I'm not expert but I think if I was going to use them I'd have to add some material on the inside so they would grip a little better.