I have suspend.
The acpi4asus developers now added support
for the U5F. I pulled their code and now I can control the screen brightness
writing numbers into /etc/acpi/asus/brn.
I also discovered that the problem I had on suspend was that the laptop wakes up with some weird brightness setting that causes the light not to turn on.
Writing to /etc/acpi/asus/brn I can now manage to turn it on again, and I
added trivial script that save /etc/acpi/asus/brn on suspend and restore it
on resume.
\o/