I did not try the Onda but it visually seem close to the Ketos 1200 cm 2 I have ; for my weight , I think that the optimum wing to ride with comfort in marginal wind is around 1000-1100 cm2 but with a higher AR than the Ketos 1200 cm2. For example I would get a better low end with a shape like Ketos Freeride 2 XL that I tried this automn . Indeed the planning with the 1200 cm2 is really early but it has so much drag that speed generation is a bit limited to get more inertia , line tension and ease the jibes and lulls. I get almost the same result with my smaller proto Easy Ketos, around 850 cm2 with higher AR. In your case 1200 cm2 like your Onda is a must in low wind IMO. Very thin lines count also.
The weight of the rider has a huge impact (it is not really fair in that sense ...) ; so comparing your optimum to mine is not easy with your +50% compared to me. But even with my 60 kg, I need more than 11 m2 to get up in my own low end ; my limiting factor becomes the ability to lift the ass from water (provided that the kite is very stable otherwise it is the limiting factor in on-shore winds).
I would just add that the stability limit of the sonic 2 need more wind than Pulsion; hence if you use a more stable kite, you would go in the water with lower wind, then you would need more surface than 11m2 ; given your weight I have no doubt on this need of larger surface.
Generally, it is really difficult to compare low ends limits between different riders reports on forums, since it is hard to assess if we actually speak of the same wind speed (even with the best unbiased intentions, it is just so hard/subjective to give a speed number below 6 knots) ; what I can just tell you is that when I ride comfortably with the Pu 15m (a bit more limit with the Pu12m but still possible) , I mean real ride with the 850 cm2 wing, say 3 times the wind speed, upwind, transitions, toe side, and some fun stuff on the hydrofoil ... then at that moment some (several) 80 kg guys with a sonic2 15m nor speed4 lotus 15m barely go to the water and then cannot waterstart during hours. And when the wind drops even lower I can still save 0.5 to 1 knot with the Pu 15m plus ketos 1200 cm2. It is not just me , another rider came with a Pulsion 12m, 70 kg, 1200 cm2 custom high AR wing, and was also able to ride at its second attempt (and relaunch from water ! I have a video of this if you want).
I hate to say THIS kite is better than THIS kite and I try to never fall in this trap . Overall it is rarelly true for any kite even if articulated briddle systems
. That is why I tell you that Sonic2 will go faster as soon as you can ride with it. But now focussing specifically on the pure low-end and plug-and-play in marginal wind, I have no doubt on this light Pulsion, from my experience, other owners (and rider applausing from the beach... so nice). No pretension here on my skills just try to put some smiles on the forum.