The difference is that while Sen Brown may not filibuster someone like E. Kagan, he will vote for someone like Alito. Not only won't Warren vote for Alito, she'll filibuster him.
I don't know why people make things like this so complicated. If you don't like Brown, primary him. If he survives, vote for him in the general.
Btw, anyone who said Brown ran as a conservative wasn't paying attention. He admitted he voted for Romneycare and would vote for it again. He said things like “it's not about republican or democrat, it's about commonsense”.
He has voted exactly like anyone should have expected. As yes, he is superior to the woman he was running against.
But here's what people don't get: Warren will not be a pushover. She has a compelling story, and is not an ivory tower liberal. She is more Ralph Nader, and less Nancy Palosi, and I'm not sure how it is all going to play out.
*Pelosi