Hi ghostship2, sorry for my late reply. That is a really good question and i think that you are right.

The most figures with 8K textures that i found have PNG files for the texture maps but sometimes they use TIFF files for bump or normal maps.

But our problem in "Power world" is that these files are very huge and my graphic card won't like it (Only 6 GB ram -> cuda error).

For my render "back out of hell" i have to cheat a little bit. This model has a lot of polygones so i use for the upper torso the 8k textures and for the lower torso only the 2k textures.