One of the most spectacular political conjuring tricks of recent decades occurred in 1993, when Labour somehow managed to convince the media that a new system for electing the party leader which accorded wildly different weightings to different votes - and which, furthermore, allowed many people to vote several times - could perfectly reasonably be characterised as "one member, one vote". That illusion finally seems to have worn off, with many journalists pointing out the anachronism of a few hundred parliamentarians holding a third of the entire vote, especially now that both the Conservatives and the Liberal Democrats have a straightforward OMOV system (although of course in the Tories' case this is only part of the story, since the MPs have the absolute power to draw up a 'shortlist' of two for the members to choose from).
So, by all means Labour MPs should be stripped of their outdated special privileges. But that still doesn't really tell us what OMOV would actually mean in Labour's case, or indeed what the outcome of this particular election would have been had it applied. If only full Labour members had voted, David Miliband would have been the clear winner. But how can payers of a trade union political levy that keeps the party afloat be reasonably denied their say? So perhaps OMOV could be interpreted as meaning that the votes of trade unionists and party members should be treated absolutely equally, in which case Ed Miliband would have won in a canter. But, there again, wouldn't it be an affront to Labour members if their full membership subscription gave them no greater clout than payers of a much more modest union levy?
I'm not sure there is an elegant solution to that dilemma, but if Labour ever want their internal elections to have any sort of democratic credibility, I'd suggest that at some point they're going to have to jump one way or the other.