In answer to both your queries, it's probably good to emphasise that I really like my current setup. I really enjoy riding it and approaching my next purchase from wanting to build on this; rather than thinking anything is 'wrong'.
Hence I'm looking at more Union bindings and another Endeavor board!
I just want more manoeuvrability and a little more 'bite', which more experienced friends assure me I'll find in a shorter, cambered board.
I'd like two to take away with me and am definitely ordering this 153cm.. Just need to decide which bindings for powder!