Never ridden the 15 2015 dyno, it's not like demos grow on trees around here for these race kites. Only reason I got to try the 13 was because the shop guy is sponsored by North and got one. We still maintain its the best kite we've flown for us and both of us have been around since the early days. I'm a good rider, he's unreal, even on a raceboard and that spider monkey stuff (although he rarely does it much anymore finds it boring as bat shit).
The 13 slowed down it's doable for multiple board of rotations, but it asks something of your technique. It is a 13 after all and its a damn fast one at that. But that shop dude has it on fast settings (both using 27m) lines and he has it on the outside bar setting and still pulls off inverted rotational board off stuff, but he's just one of those freaks so I wouldn't go basing my kite choice on that. (Which always makes me laugh when they show the promo vids...useless as shit on a stick for most mortals to get an idea of whether it suites them or not).
So the 15 would be much easier to do what you said, but it's not a no brainer kite, you'd have to have your technique at least somewhat sorted.
The rebel one the other hand is very forgiving, gives far more hangtime than say the 16m dyno and has a better bottom end. I should know, we have three 16 2011 dynos between us so have ridden it with the rebel on the water enough times to know. Thing is they probably have similar top ends, for some reason the 16 hits it's top end fairly quickly and observation toby made a long time ago and the reason why his smaller kite has been a 16m rebel.
I agree with toby on this. What I don't agree with is the rebel 18 is a good light persons airstyle kite. Infact I'd say that's total bullshit from my experience. Their is so much static grunt in the 18m rebel I just found I did not have enough Kg, even on a small board on flat water to convert enough of that grunt into vertical height and hang. I'm only 74kg but always hold down bigger kites than most 90kg guys around me, so it's not technique. It's just fkcn physics. Toby's just a freak, in a class of his own in this arena.
So I still maintain the rebel is a great weapon for the average l(I mean average rider like most of us) larger guy trying to do Airstyle...especially trying to really advance quickly. It's so damn stable, so forgiving, gives perfect feedback in the air during rotations, and if you have enough weight can be a weapon from 15 knots and up. Rotations...just go nuts, so you have so much time to adjust, it gives you the freedom to try all sorts of crap you wouldn't normally try.
I'm not convinced it suites a smaller guy like me at all. I've tried and tried and tried. Changed nose line lengths, tuned bars differently, you name it I tried it. Had some mind bowling sessions though, but overall it's just too damn big and grunty for me. Hence why I'm selling mine. Right now I've accepted less hangtime and height actually (you get this rebel right and man she gives you some scary height in 20 knots) on the 16m dyno. Being light isn't always the holy grail for kiting....most of the time it is though