People can leave whenever they want - They can do that now as well, as the lock out doesn't happen until you kill the boss or get your drop (In case off CT). Point is invalid.

People will leave after boss is downed - Happening anyway. Depending on how CT is made the incentive will be way bigger even, because you know 100% sure you won't get anything else out of the raid. Point is invalid.

People can be rude - Lolwut? Wut lol? This is just nonsense. Point is invalid.

It promotes instability in FCs - And this system doesn't do that? What nonsense. If a player is in a static for Coil he can't help his FC at all. But hey, that's not a source for drama? Same goes for CT. Why bother rerunning it after you got your weekly drop? Point is invalid.

Seriously, all your supposed cons are pretty much nonsense that will happen in any system because they're based on "people are jerks". Well they always are, no matter what system you put in place. People being jerks is simply people being human.