Thanks for all the good info!

At the moment, i will keep working on the "core", that's where most of the effort will go anyway. the "presentation" layer must be independent and i will choose the best options when i get to it. In this way, also, the core will be much more independent too.

Anyway, i believe the path is still not clear.

Widgets are not good for mobile, not supported and not working properly.
QtQuick is fragmented (1.0 Symbian, 2.0 future, 90% easy to port, but i would still need to maintain two ports)

Probably i will make a Qtquick 1.0 UI for Symbian, then see if it's worthwhile to upgrade to 2.0 for Android or choose a Qt-less solution. This will depend on the state of Qt integration with Android in the next 6 months.