Oh I also upload Q8_K_XL for eg, which will upcast important layers to BF16 / F16 as well!
Oh the blog at https://docs.unsloth.ai/basics/unsloth-dynamic-2.0-ggufs does talk about 1, 2, 3, 4, 5, 6 and 8bit dynamic GGUFs as well!
There definitely is a benefit for dynamically selecting layers to be at diff bit rates - I wrote about the difference between naively quantizing and selectively quantizing: https://unsloth.ai/blog/deepseekr1-dynamic