Can anyone advise me on the suitability of fixings in particular screws for Tanalised timber?

I have looked on the Lonza site and downloaded their user guide to working with tanalised timber and it seems there are two recommendations either stainless steel screws or galvanised screws. Stainless steel is out on cost grounds it is only a shed I am putting together. The Zinc coating on galvanised screws is regarded as a sacrificial layer so the thicker the coating the better. I have had experience with galvanised screws having secured some palings on a fence with hex head BZP coach screws the idea to be able to remove palings for maintenance reasons. When I did remove them the screws were rusted on the threads but not rusted through.

So how do the likes of Turbogold, passivated Zinc and some of these other green and blue coated screws cope having been driven into tanalised timber?

Richard