How much does the bag hold? Heaps! I got the 5'3", and it came with the larger of the two bags.
Easily holds board, pump, all included accessories, Pulse 7m wing, drysuit with layers, booties, helmet, and a few leashes!
I weighed it with all that gear just for fun - 22.5kg, whoa! Given the dimensions of the bag, I doubt one could travel by air and not incur oversize luggage charges, the general standard is 62" L+W+H, and this behemoth far exceeds that.
I think the board could be folded more narrowly, and fit into a standard large suitcase, along with the pump and probably the wing.
Between that kit and my foils that fit in a hard shell golf bag (16kg,) I'm loaded down with almost 39kg of gear - whoa!
see photos below