I've worked with devs who used Canary as their default browser. Two bugs during my time with them were bounced back with "Cannot reproduce." This was because they were using Canary.
In another instance, though, a dev tested in Canary and fixed a bug on a site before it hit the users.
This is my experience – sometimes I fix/work around bugs before users get them, sometimes you have to accept a site is broken in Canary, but you know it won't be in the stable builds.
I've worked with devs who used Canary as their default browser. Two bugs during my time with them were bounced back with "Cannot reproduce." This was because they were using Canary.
In another instance, though, a dev tested in Canary and fixed a bug on a site before it hit the users.