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About update 15.4.A.1.9 Android 4.3 for Xperia M and something more: http://au.ibtimes.com/articles/554438/20140602/sony-xperia-m-dual-certified-new-firmware.htm#.U42tD5... also http://www.sonyrumors.net/2014/05/29/sony-xperia-m-update-15-4-1-9-coming-globally-june/ and here http://www.pcnexus.net/2014/06/sony-to-update-xperia-m-to-android-43-154a19-firmware.html 
Found a link with the update. Its an open source archive. Dont know how to use it. Posting the link if anyone wants to try it out.
At last i got it 15.4.A.1.9 :smileysmileythumbsup: At this time downloading and installing with Sony Update Service (with full reset and update, so update will be clean)
Size is bigger than was previous, now is 686,2 mb, was about 20mb less 
SCREEN SHOT:
p.s.: I did not saw what's new with this update yet, but checked is move to sd feature... sorry, guys, Sony still didn't fix that, we still can't move apps to sd card... i hope at least gps and others bugs will be fixed... 