Hi, I've deodexed the /system partition to the most recent update (at the time of writing), 15.4.A.1.9, of the Sony Xperia M SINGLE SIM.
The files have been taken from the C1904 ftf, but will work perfectly fine on the C1905 too. The deodexed files come in a neat .zip for if you have an unlocked bootloader, if you don't have an unlocked bootloader please refer to this guide on how to push the files to your device.
I have also modified the services.jar file to enable SUPERUSERMOD, just push the new file to your device and enjoy. You also need to be deodexed to use SUPERUSERMOD.
I will keep this thread updated if any new firmwares get released. Just check back after about a day and I should have them up for you.
I never actually stated how I made these files, for the deodexed files I used the Kamome tool (thanks for your tool @AndroPlus) and for the SUPERUSERMOD I followed the guide by @DavidMKD.