It's not the extract vs all grain that's the question here it's whether or not you can provide the correct temperature range and control for lagers. The beer will need to be fermented at 48-55F depending on the yeast strain. Ten days to two weeks in primary is typical. I also like to follow with a similar period of secondary fermentation. The actual lagering should be done at as close to 32F as you can get (at least 40F min) for three weeks or more. If you are brewing a light colored lager extract brews tend to be a bit darker than all grain recipes.