I don't even like using, or seeing used, speedbrakes with Flap 5. You start feeling a horrible vibration through the airframe, and I hate to think what it is doing to the flaps! At that speed the effect of the brakes is very limited, so I agree it is better to mkae judicious use of early gear rather than hang on brakes. As for coming down the AGP GS with brakes out, not me at all! Flap 10 gives you more drag if you want it. Brakes just shake you.