Yes, it works on both. The lift helper spring is nice to have but can live out. There was some for sale on weekend freedom machine site also come up for sale on ebay. they sell for 20.00 to 40.00 you need one for the 110 or 112 sf or 200 series.
The helper spring sells for an incredible price most of the time. I've seen them go from $120 - $250. If you got a good left arm you can live without it and use the Armstrong lift! The blower can be a bear though when it gets packed with wet snow!
I do the armstrong method. The blower isn't heavy at all. I hear the tiller is a workout, though. If I found one of those, I think the spring would be necessary, but the blower and blade are light. I lift the blower probably 15-20 times when I do snow removal at home over an hours time, and it doesn't get bothersome.
Since everything is relative, I'm 6'3", 285 lbs. I've had enough wet snow in the blower to make me "work" at lifting it. Mind you I'm not in the shape I was in 15 years ago but it did take some effort. I like the 318 with hydraulics......work smart, not hard!