Why not both? Insisting on a very stable API can result in long times between releases, which can mean more people using tip. That's distinct from how stable tip is.
Given the frequent complaints that the previous stable release isn't very stable, I think trying to interpret it as "tip is super stable" is wishful thinking. Tip is currently less bad than stable. The fact that stable releases are not stable is a bad thing, not a good thing.
What does stable mean? If stable means there are not unexpected crashes, then Go 1.0.3 is extremely stable.
If stable means suitable for production, Go tips vastly improved performance, especially in regards to garbage collection, make it more suitable than 1.0.3 for large/high-scale applications in production.