I've turned my head away from mobile development for now with C2.
I started a brand new project to enter into the Tizen competition. It was a low-graphic platformer game split into somewhat small layouts with physics. I'm very confident with optimizing events and know which events would be more detrimental to performance and to order events and everything, but when I got round to discovering the Tizen emulators, I tested it out and found the FPS was at 10-15fps. I designed the game in mind to be low-quality and not have much media (not many sprites, ect) but I got a low FPS on a device that supports native HTML5. I think it may have been to do with the Physics objects so take what I've said with a grain of salt, but I'd only have less than 50 physics objects, not all would be active at once either. But yes, I never intended to do mobile games anyway, but after making a super simple game that didn't even look too pretty wasn't performing well on mobile, I've given up for mobile.
However, Node-webkit is a godsend and this is what I primarily wanted to use C2 for in the first place! Whilst I'm aware people are asking for native mobile compilers, I think I speak for everyone when I say that Node-Webkit is literally perfect (aside from when Chromium ends up updating with really stupid things ¬.¬ ) and if C2 was to make Native exporters, then Win/Mac/Linux wouldn't need to have one (Unless ofcourse there was a massive performance boost somehow ).
I've begun making a more detailed game with lots of WebGL effects and more physics objects and lots of customisable equipment for multiple characters that can be onscreen at the same time, and the game would run at 60fps on an old dual core with intergrated graphics (AS LONG AS THE GAME IS DESIGNED CORRECTLY, certain options need to be done, including setting the "Fullscreen Scaling" property in the project's settings to "Low Quality" and changing the canvas size + zoom in/out depending on if the player has chosen to have "Low Graphics" mode in the options menu. Without doing these extra things, the framerate would be 25fps or less. )
But again, old laptops are getting playable speeds on a pretty, sprite-littered, WebGL-ridden game. C2 is phenomenally brilliant for Desktop games!
The only bad thing about Desktop that I can think of at this moment, is the files that contain your exported game are far too easy to extract and I feel it needs at least some form of low-level encryption. I totally get that if someone wanted to extract protected files from a game, they'd find a way, therefore this doesn't really affect me, but I could see this becoming a problem in the future, allowing people to blatantly and easily spoil the game or spoil in-game secrets, especially since the filenames are named after the Sprites name in the editor (iirc).
I'd see myself turning back to mobile if I see others are really happy with whatever exporter (XDK looks hopeful!)