Edge is fine now. I think it's superior in tablet mode because the virtual keyboard comes up automatically, so I prefer it as I use mine as a tablet 80% of the time. Hopefully, a coming preview includes extensions so I can ditch FF for good. Or, if FF gets their app together with extensions.. Either way, don't care what I use as long it's touch tailored with extensions.
I am aware of the setting since they introduced the button, but it hasn't ever automatically invoked the touch keyboard in FF. Just tried it now and nothing comes up when I click on the address bar or input box.