Has anyone ever mounted the Sig Romeo1 onto a 226S.
If so are there any special mods that need to be done in order to get it to mount?

The Germans have this in their 2018 catalog. It's an Allround with the Romeo1 on top.

I don't know if there are different models, but if your 226s is the same as mine your going to have to mill the slide. And if I was doing that I would never pick a Romeo1 to do it for.