To slide head first or feet first?

There are obviously different ways to slide into a base. Head first and feet first are the basic ways in which this can be done. When is it proper to use each of these techniques?

When straight stealing, I believe the only true way to steal the base is by sliding head first. A straight steal is designed to beat the ball to the base. The head first slide is the best way to reach the base as quickly as possible. Momentum is not lost by sliding feet first. Furthermore, the head first slide allows the base stealer to use his hands to reach the bag rather than his feet which he has much less control over.

The feet first slide is used in a beat the force situation where the runner must see the play in front of him. The ball is hit on the ground and the runner slides feet first with his eyes up so he can see if the play is in fact made on him. If the throw is elsewhere the runner sliding feet first needs to see if he can advance. Advancing is easier if you slide feet first.

The simple rule of thumb is- if you think you possibly advance another base after the play is finished then you should slide feet first. If your goal is simply to get to the next base as quickly as possible then the head first slide is the way to go.