Is that the correct link? I've never heard of A40s, the link is to release notes from a year and two months ago, and SD XL just came out a month or two ago. Hard for me to get to "SD XL cannot [be finetuned effectively]" from there.
The team was given early access by StabilityAI to SDXL0.9 for this. You'll have to test it out for yourself, if you're interested in comparing. From my experience, it is a world of a difference between the NovelAI and WaifuDiffusion models in both quality and prompt understanding.
Note, the very baseline I set for the WaifuDiffusionSDXL model was to beat their SD2.1 based model[0], which it did not in my opinion.
> The team was given early access by StabilityAI to SDXL0.9 for this.
SDXL0.9 may have been a worse starting point than SDXL1.0, and certainly there's been more time put in and experience developed finetuning SDXL in the time since WD trained against SDXL0.9 by the people who have released the huge pile of finetunes that have been released since.