Having to run through 1000s of watchers in a digest cycle is not unusual with a typical Angular site and oftentimes most of those watchers are redundant.
Are there any benchmark results available? They mention it increased speed, by a lot, but don't give any numbers -- instead point to a code repo where you can run your own. This is great, but I want an "at a glance" numbers on a variety of platforms so I can verify their claim and then take it to my boss to push through an upgrade. An "executive summary" if you will.