I installed 10 preview on a 928. It is mostly good. However, I do not have any backup of 8.1 anymore because Verizon backup doesn't work anymore with phone 10. Phone 10 backup only with Onedrive. I cant goback to anything but wp10 backup done in onedrive. I tried all Microsoft, nokia recovery software, hard reset etc. Believe me. Surprisingly, when my phone boot, a little red message appear on the lower left of my screen (not for resale). It looks like Microsoft took over my phone.....for free, for free research. They should send me another phone. However, I am sure they protected their butt with the long text nobody read.