Mounts are faster, unless you want to take certain shortcuts.
Like belle to mod, can't jump off the cliff, so you use a draisine.

There are also a few areas that are only accessible by using the railroads.

The train one is the coolest. 2nd would be the christmas one. Hope they add more, obviously they have no extra function, but looks nice collect them.

Unless, they can make draisines go faster by price range...
"Power of christmas spirit"
"High powered engine"

The one with the sail is a pretty good example. Reminds me of avatar.
http://vignette4.wikia.nocookie.net/avatar/images/9/94/Sandbenders_using_a_sand-sailer.png/revision/latest?cb=20140404203810 (Unsupported image host)