How many companies test their websites in pre-release versions of Chrome or Firefox? Some brave volunteers on the team (even non-developers) could dogfood test Chrome or Firefox Beta (or even Chrome Dev or Firefox Nightly) as their regular browser for day-to-day work. It’s not full test coverage of your website, but they would identify major breaking issues before your end users do. They might find be new browser bugs that Google or Mozilla should fix or breaking web API changes that your website needs to adapt to.