Hello there, and thanks for your time.
I own a Huawei W1 ( i wish i had a lumia 620 or something...) and i just reset it, to factory settings. all new and clean.
i did ALL of the steps you described above, before reading the article. Then i downloaded the dev prev, and logged in and enabled updates.
i got 1 update... now im on OS version 8.0.10521.155 . it is gddr3 i guess. i have the app switcher for example- i already had it.
But: i followed the same steps on my fathers 520, he got this update, then an other that said: let us prepare you for wp8.1, and NOW im installing 8.1 on 520, with 4.44 gb free on phone.
My W1, didnt get the "pre-8.1" update - let alone the 8.1 itself.... Any Ideas ?! i have 1.54gb of phone storage free...
FYI, our 520 bought from greece, is set to "greece, greek etc" while my EU, bought online, W1, is set to US all the way !