Has anyone done a in-depth comparison between Qwen-3.8 27b @ 8bpw and Qwen-3.8-FN @ 4bpw?

Title says it all, I run dual 3090s (check out my post here for my setup ) at int8A16 and have been wondering if I'm missing out with QFN. There's posts ad-nauseam on reddit with low bpw strata solutions that run on heterogeneous systems, however those don't interest me - I want high precision. I'm considering selling my setup and getting a DGX Spark, since that can run QFN at nvfp4 with a large context window. My use case isn't coding but generic agentic use case - I use hermes as a personal assistant and with openwebui. If anyone's able to run both and do a comparison, please let me know!