Full-fat yogurt has fewer calories as carbs percentage-wise. That's what counts.
Another benefit of the full-fat version is that it is higher in fat-soluble vitamins.
Also, lactose is much better for you than fructose or sucrose as it's all converted to glucose. It does spike insulin, so it's best eaten post-workout if you are insulin resistant.
F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.