No experience with prior Union bindings but I've got a set of 2014 Union Contact Pro and Factory bindings. I rode my contact pros a week ago with 2014 Burton Ions and didn't have any problem with the toe straps shifting or anything.
If they're similar to Raiden that would be awesome. I feel like Raiden's design is one of the best, at least for my boots it is. I've never had problems with Union's straps moving on me in the past, but they did feel a lot bulkier than they needed to be.