Slow down lads...
Three major version releases in under a year? What's the freaking rush???
You already have the better browser. However, how about letting your developers catch up with your current browser before kicking up the version number.
I have not upgraded to V4 yet as 3/4 of my add-ons do not work with it. Here's a tip kids. The functionality I find in my add-ons is of more value to me than the browser. So unless you plan on building in the same functionality as my add-ons into the next version I am not upgrading.
That, or let add-ons WORK with future releases without having to be re-coded.
Switch to decaff, take your time and slow down the major version releases. Stabilize the version you have now, before moving on.