Matrix feels sluggish and under-responsive while Hipmunk feels crisp and snappy. Even if every other feature were the same, Hipmunk wins for that reason alone.
That's true but you can't really make any statements about that until you know how much traffic each is currently processing. A newcomer always has an initial edge there. But if hipmunk manages to keep their current speed they'll blow matrix right out of the water.
The good news is most of our work is done client-side, which scales quite nicely.