I say go with the [item]Girdle of the Fearless[/item]. Drops are never guarenteed, so if you can get an upgrade with out waiting on a specific drop, take what you can get your hands on. As long as you still have 104% total avoidance with Shield Block active, you can afford to lack a little bit in one area of avoidance, though aiming for about 20% in each is a good goal.
And if dumb DPS won't slow down on their threat, let them die. If it doesn't hurt, they won't learn. When they realize they are spending way too much time on their back and can't /flex their epeen because they aren't putting out damage while dead they will understand their flawed ways (hopefully). If that doesn't get them, then 50G repair bills from one Karazhan clear will. If you really are having a hard time holding threat, I would suggest maybe some of the following:
1) Put talent points into Improved Heroic Strike.
2) Put one point into Anger Management.
3) Put one point into Unbridled Wrath.
4) Ensure you are using the best threat rotation you can (Shield Slam, Revenge, Devastate, Devastate, repeat).
5) Spam the heck out of Heroic Stike if you have the rage (thus the rage friendly talents listed above).
6) Stack some +Hit up to 9%.
7) Stack Expertise up to 6.5% reduction of Dodge/Parry.
8) Stack more Shield Block Value to maximize damage done by Shield Slam.
9) Grab some Haste Rating gear to maximize incoming rage and Heroic Strike spamming.
If your threat generation issues are not based on your attack rotations or talent placement, then stack more Hit and Expertise rating. You need +9% Hit to never miss with your specials (yellow damage) against a level 73 boss. You need enough Expertise to reduce Dodge/Parry to 6.5% to remove Dodge from the combat table for a level 73 boss.
Good luck to you!