Depends how much snow you need to move. The single stage units are generally preferred for residential use as they clean down to the hard surface. If you get large dumps or need to clear a gravel drive way the two stage is a better choice. Snapper makes good product, but check for excessive wear on the paddles and scraper bar, they may need replacing. They take a beating on all single stage machines.

Is this a unit with a two-stroke engine? I'd be very careful buying a used two-stroke. Most people use crap gas and cheap oil, and often fail to mix the two appropriately. A scored piston/cylinder from a couple minutes of running with the wrong gas/mix and your $300 "deal" becomes a $300 rip-off.

Like canguy said, the best choice of machine depends on what you need to do with it. Paved sidewalks with small-to-medium snow dumps will favor a single-stage machine. But if you get heavy snow dumps, lots of wet packing snow that loves to be turned into snowmen, or if you have to blow over gravel/grass/patio stones/pavers/etc., then a 2-stage machine will be appreciated.

In my youth (highschool, college) I did snow removal as my source of winter income. I handled 20-30 residential accounts in addition to my parents' home, plus the neighbors of my accounts who needed a hand. I worked solo and did the whole thing with snowblowers and shovels. I ran a Toro CCRPowerlite and a CCR2000. I went through belts, paddles, and scrapers at a fairly rapid rate, but these two machines held up with proper maintenance to eight years of this kind of usage. So long as the surface being cleared was smooth, these machines were superb in the sort of snowfall that we get in southeast Michigan. When I gave the machines away before going off to grad school, they were still in good running order.

I'm now running a vintage 2-stage (1968 JD) for my house and the three neighbors whose drives and walks that I clear. It does not clear as closely to the pavement as the single-stage machines, and it is a LOT heavier and more bulky, but it does a superb job of clearing snow off of my paver walks, the gravel area where the dogs do their business, and the walkway across the yard to the wood pile, the dog area, and to remove the snowbanks that accumulate along the side of the sidewalk and driveway when I do a few snowfalls in a row with a shovel.

So figure out what you need your blower to do and the answer should be clear as to which one to get!