Hi,
the 500% bump setting should be fixed in Carrara 7.2, it was really annoying in 7.1.
I imported the same scene (Stonemason mediterranean) into 7.1 and 7.2 and the
results look very different.

With GC, the issue is that Carrara does not apply inverse GC to textures like Poser,
so you have to manually adjust all your textures in order to avoid double GC, which
makes the images look too bright and washed out.

Best regards,
   Michael