There's absolutely zero news or rumors on any further support for the Ativ SE so right now the guide is your best option for pursuing Windows 10 Mobile. A lot of people worked really hard on the basis for the guide for many months and they did a great job. I've been running stable for about 2 weeks now. Very minor bugs related to the fact that it's an insider build but no compatibility issues with the upgrade itself. Very happy. Easily a daily driver. Rest easy and follow the instructions closely and your phone will work pretty much perfectly. In my opinion my phone is running much better than when it was on 8.1.1.
Hey ase, I have a question, maybe you can answer it. If I flash back to gdr3, but use the csc file meant for the ativ s (t899m) will it render my phone useless? It has the info I need for my carrier.