The Commander has promoted me (well, Private Scow) to Sergeant. Other than some new flavor dialogue when talking to the Guards, does this have any effect on gameplay? I can't think of any place in the fortress I haven't been able to access or anything I couldn't do because of rank.

It looks like the story is wrapping up so I wouldn't want to hurry and miss something. Since this was the result of finishing all the Commander's sidequests, I guess it won't have any impact in the main story, but if would be nice if there was a reward other than extra experience.