It's weird how lots of devs treat chrome as a standard, even though when developing I have a lot more issues with Chrome browsers than Firefox browsers
I haven't had any issues with browser compatibility since IE. Occasionally Safari might have some CSS issue, but it's been probably 10 years since I had any major issues with browser compatibility. Html 5 and CSS 3 tend to work across all browsers without issue.
I'd disagree on Dev tools. Both are really great and useful. What I'd say is that Firefox may have less support for external debugging, but that's more others choosing not to do Firefox debugging