Highly quantized models are crippled versions of the original model. Don't evaluate a model for a production use case based on it's quantized versions.
I find the larger Q5 versions from theBloke to be pretty good and allow you to run a larger model than you’d be able to otherwise. But there is definitely an impact, although it’s hard to quantify. It’s sort of like how you get less effective at coding when you’ve only slept 5 hours.
For example this 180B model works:
https://huggingface.co/spaces/tiiuae/falcon-180b-demo
Why? Is someone paying for it so I can use it for free?