I can try to give you an order of "lightest wind ability", and will try to "project" to 90 kg, but you need to keep in mind that I am -50 % lighter and my advice on A15 is more a projection than a real test ( I assume it is not so far from a Pulsion, maybe just a bit less agile and fast: I have just received a A15 in 9m but not tested yet and it will not be dedicated to light winds);
I would say that Aurora and A15 have both interests for you; from your PM yesterday I understand that you are looking for a steady kite in light winds with good relaunch , and you have some ride experience on PL foil ( I suppose it is ARC models like Charger or Venom); in that case I would finally risk to choose A15, but it is hard to ensure that because I know nobody having testing a A15 on a HF and in marginal wind :
- A 15 have better relaunch (easier rotation on wing, wind will be catch at higher elevation)
- A 15 will remain more stable in light winds in the zenith (certainly less prone to over flight) : this can be a dominant aspect for onshore winds when you may have to swim backward with both ends to get out of shore by creating your own relative wind.
- A15 will need less briddle adjustement (if any on the Aurora) and more stable in the time
- A15 will be easier to water-start and foil-up without good "HF pumpimg skills"
- A15 will support better lines extensions without loosing much up-end and agility (like a LEI)
- A15 certainly more stable in high winds, but less comfortable when parked during a ride with HF
- A15 more quicker turn and smoother/powerfull loop (good for waves or carving)
- A15 more forgiving in slack lines (frequent when working on transions, specially in extreme light winds when you jibe toward the kite)
pro Aurora 15:
- Aurora will give you more riding speed and up-wind angle
- Aurora will be more comfortable in straight line (more forward pulling)
- Once foiling-up, Aurora will maybe accept better ponctual lulls without loosing planning (i.e. marginal wind below 4 knots during 3-4 seconds)
- Aurora will have a better wind range (almost same low end but better high end which is important in light winds)
- Power/Depower stroke of the bar will be more efficient (shorter) than A15
- Aurora may stay similarly or better in the zenith if can work the kite (hands available) , but less "auto-zenith"
- More feed backs available from riders (and some on HF)
I also understand that you have experience with BRM clouds which will be clother to the A15. I do not fly Clouds but I understand that they have really good marginal wind ability , so I am not sure you will gain a lot with A15 or aurora (except relaunch and upwind angle that should be improved), but in any case with your weight you will need 15m and not 12m.
So attempts of conclusion :
If you have good skills to loop kites and avoid or recover from slack lines, Aurora should give you almost the same marginal low-end, with more comfort in straight line specially in high end; if you have complicated on-shore conditions, and/or high risks to put the kite in the water, and prefer working transitions / Carving safely rather than up-wind angle, A15 should be your candidate with less risks of briddle instabilities (fabrication quality or wear in time). Ultralight is a must off course; If you keep your Clouds in your quiver, I would choose Aurora 15 to gain riding speed and have a "different" kite. You may be disappointed on the actual gain of low end vs Clouds, unless you buy a foil kite which has even lighter cloth.