So it's nice to see some non-mozilla involvement and momentum in Rust/Servo. Maybe that means that an investment in learning/using Rust is that much less risky :)
[1] http://www.mail-archive.com/dev-servo@lists.mozilla.org/msg0...
That said, having an ARM backend to Rust on Android phones means big things for the potential of mobile web performance. I'm hopeful!
1) There is no uniform agreement about the state of Servo. Some are more optimistic than others.
2) There is a number of unknown unknowns here; that's what makes it a research project and makes it hard to roadmap. For example doing parallel layout of CSS involving floats is an actual research topic people are currently publishing papers on...
I'd rather see DOM-updating (e.g. via Javascript) in parallel to the rendering. Although, that already leads to problems since rendering changes to DOM as well.
Personally, once Rust stabilizes as a language, I plan to write the bulk of my "low level" at-home code in Rust. After tooling support gets up there (providing things are still awesome), I plan to use it professionally.