Default [Q] ROOTED : Unable to convert to ART now. !!

Hi,

I have unlocked my bootloader and rooted it. Used xposed for a lot of customizations also. everythng is fine...except :

1 not able to convert to ART now, it reboots and still stays on dalvik.
2 root uninstaller is not working. cant delete system apps inspite of proper root access.

Kindly give me an idea what is causing this ? Is this the S-ON ? because till now i could not find the S-OFF process for this phone, so i'm unable to S-OFF it.

Thanks
karan