It may raise EGTs slightly, but I don't think it will take them past the limit. In fact adding boost pressure will actually reduce EGTs in some cases. I think it is more of a "limp mode" so the doofus driver knows something is wrong. If you have ears (at a minimum) and a boost gauge (preferred) and can walk and chew gum at the same time it is not needed.
That being said it is still operational in all of my cars that came with a 617 turbo from the factory. I did not transfer the system over when I swapped one into my 240D though, but not much about it is stock.
ForcedInduction had a wastegate failure when he still had that old WW2 design wastegated turbo in his car. Perhaps he will chime in.