Last time they did it, personal scandle rocked the candidates and the result seemed like a messy compromise (which, as it turned out, it was).
This time the candidates are slogging it out in a most bizarre fashion - the Politics Show "calamity Clegg" issue looked like two men from different parties at each other's throats rather than two colleagues competing in an internal election. I think the contempt with which Huhne holds Clegg in is distorting his political judgement. It is getting nasty and may well cost the LibDems vote ... and as I always argue, when the LibDems suffer then all politics suffers too.
An interesting contest for us Tories to observe (Labour, of course, didn't get a leadership vote this year) given the excellent contest we had in 2005.