I notice a dramatic difference in duplicate content
titles more then the content. On a very small scale mind you but I do notice it.
I have noticed on some of my more heavily visited sites that for news feeds, they create their own page on my site via the rss every hour, they don't get cached by google at all, but all my original content does.
They will randomly pull in SE traffic on certain days, but for the most part don't even get listed in related serps.
So for instance one of my sites has around 14,000(17,000ish total) pages made from the RSS feeds, but only 3000 cached in google that return results. All 3000 (just under actually) are 2000 word + unique articles, plus forums, social etc..
So I havent had any penalty from them, it seems that google realizes this is useful info to my users but at the same time I get no "weight" for it.
just my
edit: by dramatic and small scale in the first line, which contradict each other, I just mean It's day and night, but also not like I get alot from it. Change = a little . duplicate title = nothing much but a SE bot basically