Need advice on this SNG situation (Daliman? :p)

[Lucy Alexis Liu]

In situations where there are 4 players left, everyone has folded to me in the SB, and I want to steal - with 700 left and blinds 50/100, is it wrong to move all-in or should I raise to say 300 instead? BB has 1000 (I'm thinking about the rule of thumb that if one's bet is about 40% of one's stack - then it's better to just move all-in.)