Tamron 24-70 f/2.8 - Safe to buy yet?

i just received my new Tamron 24-70mm and tested the stuck aperture issue and sure enough it's still there

The problem only manifests itself when you go from f2.8 to f4; the lens seems to be stuck at f2.8 for I can see the image overexposed by 1 stop (even though the speed did change to double )

Now if you go from 5.6 to 4 then there's no issue

The issue does not warrant a return of the lens for it performs flawlessly otherwise

maybe Tamron can issue a firmware update in the near future?

As for now just underexpose 1 stop should you switch from 2.8 to f4 or fix in PS

Cheers,