Infraction: Please make sure the information you post is correct.
Message to User:
Multiple people reported your post or posted in the thread that you're wrong. You're welcome to PM me about why you're right and I'll take it into consideration. However, I have this crazy hunch you have your facts mixed up.
Using Sunder is a benefit for the single warrior as you can't ignore all the armor a boss has. If I'm not mistaken there are 13.xx% remaining at a lvl 83 Boss; even if the tooltip says you're at 100% (Thanks again for making figures "easy and clear" like at expertise...anyone? ;-) ).
That said you need 2x Sunder + FF or 3x Sunder to have maximised DPS. For the whole raid the benefit is even bigger as you have multiple phys. DPS which might not be ARP-capped.
Including Sunder in the rotation is not that hard. There are a couple of free GDCs. If you're getting used to it, you even can manage to keep Sunder AND Rend-Dancing within your usual "rotation". Even if you had an extrem luck with Slam!-procs I'd drop one Slam for the sake of keeping up a 5 stack Sunder.