GPWS Pull Up climb gradient

[ExMedevac]

This info is probably hard to find in manuals or any generally available written form so I must appeal to those who have more experience in this area:

What kind of climb gradient can one expect from a modern airliner in the terrain escape maneuver, i.e. GPWS Pull Up? This would assume throttles to the firewall, clean, pitch up initially 20 degrees, and then up to the stick shaker. I am mostly interested in the A320/B738 type performance, but any other type info is appreciated.

Thanks