I agree with your take on the grandparent post's use of 'liberal' as a pejorative, but I have to take exception with "there is ample room in the Democratic party for self-identified moderates." Just look at how Lieberman has been demonized. On abortion, civil liberties, education, gay rights, he is on the left. For foreign policy, he's hawkish/to the right. He's about as moderate as moderate gets, but if many people on DailyKos/MyDD had their way, he'd be out of the caucus. Too many people on this site don't want the Democrats to be the big-tent and moderate-inclusive party.
This poll is TOTALLY meaningless because of one very important fact: voters are not 'taunted' by what the Republicans will do. Not only does this not show Clinton performing worse than Obama, it doesn't show either of them performing badly for the downticket races to start with.
So if I'm "Big Bad Evil Corporation," I can get rid of a candidate I don't like by giving $2,300 to them? That's an awful lot of power to be giving to the bad guys, Hugh. Don't the stances a candidate has taken in his/her career matter more than how that person makes money? What's it matter if she bankrupts Walmart taking their donations if she does the right things (which she has)? This 'corporatist' boogeyman is flat-out silly.