I don't know much about his backup at LT, Butler honestly. Duane i'm pretty sure has never missed a game and has started every one. Some are saying Butler may be better in pass protection, I find that hard to believe since he'd be starting at LT if that was the case. He does get some snaps though. Also we've signed Ephraim Saalam, who does have his moments and ummm from what I remember of him when he used to start used to look horrible. I'm thinking Kubiak will split the time between him and butler like we do at RG.
The good thing about Duane is he does get better the more he sees one guy, for example Freeney dominated him when they first met up. Now it's a more equal battle definitely. so I expected Ware to get a sack or two on Matt.
You're right about chip blocking and doing everything they can to protect Matt. I expect we'll see a lot of Dreesen the blocking TE if it gets too bad though...at least I hope. I guess the good thing about Duane is he rarely just gets destroyed and blown up, which is good because it means Schaub doesn't take many blindside hits he's completely unaware of, that's what i'm worried about.
As for Butler from the little i've noticed him playing he seems to be a solid backup. Still expect a lot of pressure from Ware though, good thing for the Texans is that the rest of the line is solid. If it gets too bad it's time for the Texans to make use of the 8 TEs or so on the roster.