Interesting, I received the 5.0 update 2 days ago, on my "Angry Bird" Roku. I just checked for an update and did not notice it was to downgrade back to the 4.9. Now, I am bummed. Has this happened to anyone else?
As mentioned on this forum many times, Roku often does an early roll out of new firmware versions to a subset of users for testing purposes. When they do that, they intentionally allow those users to revert to the previous stable firmware via a manual check in case the early release proves to have problems. Roku does not otherwise allow users to go back to old firmware.