agree that six max is different than longhand. agree with what you are saying, but two considerations for a smaller EP raise:

1. raising UTG = you have less information, so a large raise with QQ is undersireable as you will be big trouble if you face a large reraise, and will chase a lot of the hands you have dominated. This is less of a problem on the button as you are aware that you almost certainly have the best hand, and will have position for the rest of the hand.

2. because of the tendancy for CO/ button to put in steal-raises (esp shorthand), you can get away with a larger raise because it will be respected less.