The general fact now is that glancing blows add up to 50+% of your total static damage, and you get 3 of them. Twitching animation adds ~15% to attack speed but sacrifices glancing blows. It's agreed by most that glancing blows add more damage than twitching, EXCEPT when fighting against held enemies.
I twitch when I fight held enemies and use glancing blows against everything else for absolute maximum DPS. This strategy doesn't change with U9 because glancing blows aren't currently enhanced against held enemies.
Losing the chain really cripples your DPS against non-held trash, bosses, Oozes, Undead, Constructs, and Elementals: Things you will be fighting both early and often.
You really, really don't need 4 Toughness feats. That just detracts way too much from your damage output and Barbarians have enough trouble fitting in feats as it is. I've tanked everything up to and including Horoth on all difficulty levels with 1 or less Toughness feats on my Barbarian. It's just not necessary, especially with the massive amount of hit points you get from raging and up to 9 DR. Focus on Constitution and Toughness enhancements instead.
Toughness is something that belongs on a Fighter to compensate for the massive lack of CON that a Barbarian gets while raging.