I was asked today whether the international community should favor a coalition or a runoff in Afghanistan. I had not expect that question, but as I started blathering, I realized that it really depends on how the outside world wants to place its bets: on individuals or institutions? If it is just about individuals, then a coalition would be welcome as it would end the uncertainty of who governs. And you might expect that it would increase the number of folks who would be behind the government--Karzai's Pashtuns and Abdullah's Tajiks. Woo hoo.
But then again, it means that elections are not really that important, that they would have to come up with new rules/norms that would include Abdullah since there are not (at least to my limited understanding) powers that would go to a "coalition partner." This is a presidential system, so I am not sure that there is much room for power-sharing. So, a coalition would probably undermine existing institutions as the politicians would have to come up with new procedures on the fly.
Elections are ugly, but I can only imagine how ugly a coalition would be.