Open With saves me a whole lot of hassle. Some sites don't work properly in FF, so, using Open With I can quickly load the current page in Chrome or (perish the thought!) Edge. But still more useful and indeed important for me is that I can quickly load the current page in BlueGriffon, my web page editor, or in EditPad Pro. I use both these latter for working on my local version of my extensive five websites. Saves a huge amount of hassle!
One odd thing. Just lately, the toolbar icon for Open With has taken to repeatedly giving a warning message, that Open With couldn't make contact with the outside world (presumably meaning it couldn't make an Internet connection). But its permissions don't include being able to do so, so something is clearly screwy about this.
As another reviewer has remarked, it would be greatly helpful to have a facility for exporting / importing one's settings.
I found that this extension had ceased working, and presumably this was associated with the error message noted above. I followed a reasonable hunch and re-ran "[path]open_with_windows.py install", and that fixed it.