The only big difference, beside price, between the two is cost of repair WHEN you crash.

As a "newbie" you can definitely plan on crashing. 4 strokes have more parts that can be damaged in a crash. (Don't ask me how I know about that ). The pushrod tubes are especially vulnerable.

I can't tell you about Magnum 4 strokes. From what I have read from others, they are supposed to be pretty good.

If you want certainty get a Saito or OS.