No our Qwen3.5 new ones show the opposite see https://unsloth.ai/docs/models/qwen3.5/gguf-benchmarks

Am I misreading the table?

  Unsloth Q4_K_M

  PPL:       6.6053     KLD 99.9%: 0.5478     KLD mean: 0.0192

  bartowski Qwen_Q4_K_M

  PPL:       6.6097     KLD 99.9%: 0.5771     KLD mean: 0.0182

Barely noticeable drop in PPL; noticeable KLD drop (good, 5%); but worse KLD mean (bad, 5%).

You forgot to check the disk sapce - _M and _XL are not the same across quants:

Unsloth Q4_K_M 18.49GB 0.5478 KLD 99.9% 0.0192 mean

Unsloth Q4_K_XL 19.17GB 0.4097 KLD 99.9% 0.0137 mean

bartowski Q4_K_M 19.77GB 0.5771 KLD 99.9% 0.0182 mean

The table doesn't have bartowski Q4_K_XL to compare, but given the metrics of _Ms aren't universally better it's unclear if smaller size doesn't come with a cost.