Yeah, Heart of Thorns is still very difficult solo, but Path of Fire and End of Dragons are quite comfortable, especially once you get an elite spec into your build. It kind of feels like the difficulty progression was reversed, as open world play has actually gotten easier with each expansion.
As far as I can tell, they aren’t buffing the speed, but it gains a lot of new utility. Being able to mount in combat sounds quite broken, and will apparently not be possible with the other mounts.