Thanks for letting me know about this other addon! Sorry I didn't get back to you sooner, but based on their source code, the differences are minor, but enough that I feel this is a worthwhile alternative:

- This addon specifically only overrides Google Search pages, not all Google apps/subdomains like maps (since they don't all need this treatment like Search does).

- This addon uses a tablet user-agent string if you're using Firefox on a tablet, rather than just always spoofing a phone user-agent string.

- This addon adds "FxQuantum/version" to the user-agent string it uses, so if anyone is paying attention they will know that you're not actually using Chrome (which may not achieve anything, but I still feel it's worth doing so).

- This addon keeps the major Chrome version number it uses equal to your running Firefox version plus 4, so the addon may not require as many updates (it should effectively always present itself like the latest version of Mobile Chrome).

- This addon overrides the user-agent string in not just the HTTP headers Google Search sees, but also its Javascripts' navigator.userAgent value. This may not make much of a difference, but I've seen instances in Google code in my day-job where they read both, so I kept it thorough.