There seems to be a hard limit of 500 steps per image. Is there a reason for this and can this be changed? Many prompts only start to look good in the high 400s, at least with my crappy GPU
Yes. Its limited in the code (predict.py) you can always change it to a greater limit and recompile it. change the "500" for whatever number that suits your needs.
The code is the following:
num_inference_steps: int = Input(
description="Number of denoising steps", ge=1, le=500, default=50