upandgo said..
From what I can tell from the oz 12m is that the build quality while it is top end the weight around the kite is heavy compared to most 12m of similar style. i recently had the chance to take out a North Dice 12m Kite (2015) and in the light end of the 15k range flew like a bird, I was able to ride and relaunch (4 string setup) with out issues do some tricks and generate the power, and it felt like half the weight of my c4. I have also heard that the bottom end was improve in the 2015 then previous years.
This simply isn't true (in the sense that the C4 is a heavy kite). If you weigh the C4 against all other 12m 5-strut C-kites you will find that the C4 is actually the lightest kite of all of them, I notice it when I have to pack to travel, I can almost take an extra kite over people who travel with a quiver of Fuels or similar.
If you want to be correct you need to weigh the Dice against the Catalyst, then you are comparing Apples to Apples as they are both 3-strut kites

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The C4 has a good wind range, the problem isn't that it's not good in lower wind, I think the issue is more the fact that Ozone print their sizes acurately where as other brands (cabrinha cough cough) ramp up their sizing, where a kite labelled as a "12m" is really a 13m or sometimes even closer to a 14m.
To answer your question the Catalyst is indeed lighter and it's also slightly lower aspect profile to the C4, this along with the weight saving will give you a little extra in the light wind.
My other suggestion might also be using longer lines. What length do you currently use? If it's 22m or shorter I suggest trying 25-27m lines first and see how it goes. Also make sure your bridal settings on the front of the kite (near the middle) are in the longest setting possible.