Stylo (Servo's style subsystem) has already landed in Firefox behind a preference flag (not everything is wired at this point), and it also improves perf.
So, yes Servo is of paramount importance for Mozilla's future, because it does make a difference to end users.
Another advantage of Rust is that it allows devs to avoid a whole range of bugs making it easier for them to iterate and ship updates without introducing new tricky bugs (race conditions can be hard to debug).
While dynamic languages may be nice when you want to explore a problem space, the stronger/most static type system is a benefit for upgrading large, mature code bases...
Stylo is still a compile-time option, but will soon be built by default and controlled by an about:config flag. You can watch the progress to build by default in this Firefox bug:
Have you gotten amazing results on your machine? I ask because I think Servo, Rust, WebRender are awesome and I'm rooting for them, but the performance has not been great when I try Servo or WebRender in Firefox on multiple machines. Maybe it's just the machines I've tried on though.
Browser benchmarks should include how long does it take to watch a 30 sec youtube video from application start to finish or how much 3rd party feature/bloat/mal/adware it downloads connecting to $major_site.