After 7 days I finally got pixel format support ready for Zwoptex. It'll export RGB565A0, RGBA5551, RGBA4444. I've used a few images and the results are good especially for how extreme some of them are.
See Example & Info
I was just going to reach out and ask if anyone has a sample image they have had to optimize before putting into cocos2d that they would be willing to let me test the algorithms on.
If you have one please send it to support[at]zwoptexapp.com
Thanks!
Robert