I do really appreciate the degree of customization (English conversion, KeyHelper, Overclocking...) and the ease of use (Sharp-compatible)associated with the Cacko ROM. But it's true also that sticking with the Sharp applications has some drawbacks, like when those apps are poorly designed (which is the case, for instance, of the datebook application). The fact that the OZ project is open source, indeed, might lead on the long run to more optimized and/or better designed PIM apps, for instance.
For now, I keep the Cacko ROM on my 3k, as I'd really like to have a stable setup that I can rely on (well, if/when I can get my GPRS CF card working, that is... until that time, it's not really satisfying, but after all, nobody but me decided to help beta test it! ), but I'll certainly be monitoring the progress of the OZ ROM as well!