Euclid V5.1 now includes updated models in the merge as well as some extra secret sauce.
I recommend using Hires Fix if possible as it really brings out the detail, I usually use a denoise strength of 0.15 - 0.25.
I also use the SD Ultimate Upscaler at a denoise strength of 0.1 - 0.2.
I'm also using the new DPM++ 2M SDE Karras sampler which seems to be a great upgrade vs DPM++2M Karras. Please note that at the moment DPM++ 2M SDE Karras may introduce artifacts to the image. On testing UniPC and DPM++2M Karras don't seem to have this problem.