In my humble opioion, the biggest difference is price. I cannot speak for the Magnum 4 strokes, however I can speak for the OS and the Saito. Once they are set, they are no problem at all. I do use a different fuel on my 4 strokes than my 2 strokes and that is all about the ammount of lubrication in the fuel and I am not really sure that it is needed. Good Luck, Dave