I've only got 10 rocking 4 piece t 10 and pillars of might. In fact, none of my gear has expertise at all...I've only got a few guardian's gems in for socket bonuses and the six from spec.
TPS is not really an issue, and really the only time I would value more expertise (given tps being a non-issue and parry haste being disabled) is early on in the pull because an initial dodge/parry (or even miss, based off hit) can lead to an insta pull off of you. Still, to totally eliminate this chance you'd need to be hit capped and expertise capped for parry, which certainly isn't practical.
Additonally, with the exception of Heroic LDW all the bosses are susceptible to taunt...I'm in the habit of throwing a taunt on the boss as I charge in Shield Slam. It's off GCD, and while it may also miss it gives me an additional buffer period as it'll give me a second gcd with which to hit a big move if my initial SS doesn't land.
I'm actually considering ditching the 3 or 4 guardian's dreadstones I have and going back to the agi/stam I was rocking in t9, but I'm not sure I'm comfortable doing that.