Answered my own question lol! On the corporate shareholder's site:
10% discount on tickets for flights on the world's largest helium-filled passenger balloon situated in Disney® Village.
However, it says:
Offer available for Shareholders Club cards owner(s) only.
So, not a massive discount if it's only available on the SH themselves.
What's the AP discount on this like? I still can't decide whether it's worth us getting APs for next year if we decide to go twice? I'd go for the cheapest I can - Fantasy I suppose, having checked BO days there's no issue with dates for us. Both DDs won't be 'free' on offers next year - DD2 might be if I used an under 12 offer. It just seems a waste getting APs as well as SH as we get discounts with SH card, esp if we go for the cheaper AP, there won't be much, if any discount on shops etc.