Guys & gals, GDR3 preview for developer is out and those whom have registered as Developer can now download the GDR3 directly via this app from Microsoft... However, this is only updating the core OS and any firmware specific update from phone manufacturer is not included e.g., Bittersweetshimmer..
(if your phone currently has AMBER they mentioned it will still be there on your phone post upgrade) and you cannot downgrade the OS once you upgraded to GDR3 preview, one can only wait for the newer version until GDR3 hit RTM or GOLD...
If you wanna try but not registering yourself as a full developer with a whopping USD 99 or USD 19 (unlock up to 3 devices for developer), you can go to
Windows Phone App Studio to register yourself as a developer with 1 device activation to get the GDR3 preview...
You will continue to receive the official update (and firmware) when they become publicly available, so there is no missing out of features, nor will you ever be behind
This will void your device warrantyPlease read the Terms and Condition carefully before going for the GDR3 preview ya
(my L920 warranty gonna end this December anyway so let's have a go!)Downgrade?! For Nokia Device Back to GDR2 AMBER?!A user in wpcentral managed to downgrade back from GDR3 to GDR2 AMBER on his Nokia at
here... although Microsoft specifically mentioned you cannot downgrade the OS once you upgraded to GDR3 preview... that user is using Nokia Care Suite for the job!
Have fun..
P/S: Once you choose the Windows Phone App Studio route (free mar), you need to download the whopping
1.6GBSDK 8.0 +
960MB SDK 8.0 Update

to register your phone as a developer phone to side lock... If you wanna do some extras reading how to register your phone to become developer phone, then hit this
site
Upon successful registering your device as a Developer Phone, you will also received an e-mail to install a Microsoft Certificate which will allow your phone to accepts sideload or OTA from Microsoft preview channel
Once the above is done, scan this app below to get it OTA to your phone...
This post has been edited by -ahtiang-: Oct 16 2013, 08:12 AM