Windows Phone 8.1 owners who upgrade to Windows 10 Mobile will still be able to downgrade

[Windows Central]

Microsoft began rolling out the Windows 10 Mobile over-the-air update to selected Windows Phone 8.1 devices in March. However, if those folks that do receive the update decide that Windows 10 Mobile is not for them, they will continue to have the option to downgrade back to Windows Phone 8.1.

Full story from the WindowsCentral blog...