So i've made my first tries with Ejecta, and it looks very great.
It's a bit complicated to put an app on a device, but if even me was able to do it, everyone can :)
I tried a level i've done, on an ipod4 (it's a platformer, fullscreen, not optimised at its fullest, so i know the fps are not very good on that device, but it was just to do a quick try).
And the results i had in xcode with the instruments are :
(i don't know if the use of cpu is important but i put it)
ram use : around 42 mb
fps : between 30-50 (ok to play that specific project).
% of cpu use : 70-75
ram use : around 21 mb (!)
fps : between 27-35 (like cocoon enought to make it still playable)
% of cpu use : 40-60
Well, it's just a quick try, but i think it shows that Ejecta can be very interesting, depending of the project, cause it's dealing really better with the ram usage, wich is, as long as dynamic memory usage is not supported, a very important point on mobile devices to me.
I've done another try just with a scene and a tile on it, i didn't save the results, but it was the same : Ejecta was making me winning 10 mb of memory and was using less cpu.
So it seems that the more you use things, the more the difference of usage of ram is big between the 2 software.
I'm not at all a specialist of technical things, so maybe my tries are crap ones lol, and if someone can do better "real" ones it would be great, but in my case, Ejecta seems to be a better option than cocoon at the moment (and my tiles were perfectly drawn by Ejecta), cause the difference in the fps is not visible in the game itself, and i win a lot of ram.