It might just be that the version I've seen (forget which iteration) wasn't burned to blu-ray effectively or something, but it struck me that the rear channels were awfully quiet in a LOT of scenes. I'll have to test something like, say, the trench run, since that has a fair bit of "front to back" sound to it, but, like, I don't recall the Tantive IV sequence using the back channels when the storm troopers bust in, and you'd think they'd make use of it then.
Maybe I'd have to compare it to the SE DVDs.