Most things have been covered-- the only other advice I might give:
Unless you have a LOT of free time, be sure you have the toons you want to take in to t6 figured out before doing t5.  It is very likely you will not want to do another 5.0 quest from scratch for a different toon anytime soon after finishing t5 for the first time.  Pick your core 6 wisely.

Thanks for the update! 

Just to be sure you are aware, I think it would be generally agreed upon that DK/Oma were the major bottlenecks of T5.  This change will significantly decrease the difficulty of obtaining the 5.0 flag.  For reference, this change would probably have cut the time it took me to be 5.0 flagged in half-- yes, DK and Oma were that rare.

If one desired to maintain the current difficulty of T5, an alternative solution to this would be adding the shoulders/cloak as a % chance to drop off of some other bosses. 

Perhaps making White also have an X% chance to drop shoulders or cloak would be a good idea?  As it stands now, I finished 5.0 task on several toons before finishing their 4.5s due to not needing coral and the amount of time it took me to do a 4.5 run.