I’m not sure which option is to prefer. If I could wish than I would like to use all options together - compressed mip-map and only visible. 
For example I have to render complex interiors - what is better to use? Or are mipmapped textures still compressed?
This was a nice question…Never saw an answer!!!
Can you talk about it a bit please
What are the diffrence, how big is the difference saving vram with on demand bitmapping and compressed textures.?
About the comppresed textures is as fast as full size texture to render?
This was one the Best things in vray 6.1… i could not see that option in action
Does on demand bitmapping works ok?
There are a lot of vray gpu users whose like to see the difference between compressed textures and on demand bip mapping
Thanks
Hey guys!
I recommend using Compressed Textures, it is our way moving forward with V-Ray GPU.
On one side, it preserves fine details in your textures and it works nicely with GPU LC. We will remove Mip mapped textures at one point
About performance with Compressed Textures, it should be close if you have one or 2 GPUs. It will be slower if you have multiple high-end GPUs, this we plan to improve in future
Best,
Muhammed