Good but with funny name Rated 4 out of 5 stars
Very useful for web developers. Needs a better name so more people can find it. "Open With Browser" or "Open In Different Browser". "Open With" sounds like a file format handling addon. I would give it five stars but you can't fix the icon if it doesn't load correctly, which often happens in linux since linux does not embed icons in executables.This review is for a previous version of the add-on (18.104.22.168-signed).
Yeah well, it's a bit late for that now.
About icons, it's a bit suboptimal, but you can set an icon using about:config. Find the browser entry (e.g. extensions.openwith.manual.browser), add .icon, and set the value to an icon's url (e.g. file:///opt/browser/icon.png). Hope that sorts you out in the meantime while I get around to fixing it.