To tell the truth, I haven't read all the back and forth. My two cents. Megill is very important, as Murphy does maneuver Uribe and Koening around (Koening bunch of lefties, Uribe middle of the order) to match up to whatever bats are coming up the for innings 7-8 (usually).
If Megill is gone, Uribe is strictly the 9th inning, even if the middle of the order is coming up in the 8th inning. And we have no one proven to take over the Uribe role. Megill might be due for his reliever bad year, but I would still keep him on the roster.