Just got a replacement Note 4 910t3 model today, it is on 5.1.1.

So, I went ahead and followed this tut, to get custom recovery/root/sd card fix.

http://forum.xda-developers.com/note...-root-t3177225

Used this kernel to repair wifi calling

http://forum.xda-developers.com/note...990557/page286

Phone seems stable etc. Is there anything else I should know that might be different from the regular t model of the phone.

Thanks!!