I just wanted to jump in and say that while we don't yet have a target date for the release of Axure RP 9, we are aiming to release a public beta during this summer. You'll be able to find some more details about version 9 and its features here:
I also wanted to mention that you're seeing may not be a bug but actually expected behavior. As Anthony discusses in his forum post, if one widget within a group is in the push/pull path of an interaction but the rest of the group's widgets aren't, that one widget will be pushed/pulled away from the rest of the group. In either case, the approaches of targeting each element individually or grouping them all within a dynamic panel that mbc66 described would be the best way to work around this aspect of push/pull interactions.
Hopefully this helps to clarify some things!