I've never had a problem with my single stage MTD. Yes you cannot wait until the end of the storm when there is 10+ inches on the gound, but if i know there is a big storm coming I just head out when its 4" on the ground. The trick to single stage for ME is to use the impeller to "drive" the machine. The impeller has a rubberish edge for excellent cleaning. Slush.... Don't even try!
I have a dual stage now, not all dual stages are awesome. The impellers usually do not have any rubber on them, so you have to adjust the scraper on the bottom. The impeller on the 2nd stage throwers have a large gap so it's worthless in anything less than 4". UNLESS you modify them, google "snow blower impeller mod".