What does ComfyUI-GGUF let me do with quantised diffusion models (Flux, SD3.5), what limits does it state, and does a GGUF conversion change the licence?

Problem. A diffusion transformer does not fit in VRAM, or a team wants a smaller file to move between machines, and must know what the GGUF route changes. Conditions. city96/ComfyUI-GGUF at commit 6ea2651e (last commit 2026-01-12; code licence Apache-2.0 text). Targets transformer/DiT models (the README names Flux and SD3.5 Large quants) and a quantised T5 text encoder. Method. (1) Put .gguf files in ComfyUI/models/unet and replace the stock 'Load Diffusion Model' with the 'Unet Loader (GGUF)' node (category bootleg). (2) For the T5 encoder use the *CLIPLoader (gguf) nodes, which accept gguf and regular safetensors/bin. (3) Install the gguf Python package. (4) Keep ComfyUI recent enough for custom ops. (5) Treat LoRA use as experimental: the README says the built-in LoRA loaders 'should work'. What it changes. The README claims DiT models seem less affected by quantisation than conv2d UNets, which is why low-bit quants are viable on low-end GPUs; it gives no quality measurements, and the HF model card only points to an LLM (Llama-3-8B) perplexity chart as a 'basic overview' of quant types (inference: that chart does not measure image quality, so run your own A/B on your prompts). Licence passthrough. The flux1-dev GGUF card says it is a direct conversion and 'all the same restrictions/original license terms still apply'; its HF metadata tag is 'other' (flux-1-dev-non-commercial-license), while the schnell GGUF card is tagged apache-2.0. A quantised file therefore inherits the base model's licence; it is not a new work. Failure modes. Custom-op requirement on old ComfyUI; macOS note that torch 2.4.1 seemed required on Sequoia because 2.6 nightlies gave a buffer error; 'WIP' status in the README. Limitations. README claims, nothing was run here; no size or VRAM table is in the README. Version and date. ComfyUI-GGUF 6ea2651e; model cards revised 2024-08-18. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: No quality or VRAM numbers in the sources; licence reading is engineering triage, not legal advice; HF metadata tags read from the card header at the pinned revision only. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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