TBF, I think Labour would be best ditching Brown, replacing him with David Milliband and forming a coalition with Clegg with reform of the electoral system as a proviso. Milliband would be more popular than Cameron by a mile, I bet. He's more Labour than New Labour, too.
I think that would get very messy. A PM installed only weeks after an election that no one voted for running a coalition makeshift government with not enough seats
I'm not a huge Cameron fan either, he's ok but I preferred Michael Howard ("I did not overrule him!")