DeepHere's the thing, sure it does less damage, but it's more accurate, allowing you to put out more damage at mid range. Sort of like a shortstop, but with a speed boost. If you use this, trust me, you won't need to jump. The speed boost is so ridiculous, that you can easily juke heavy classes at close range. Why would you ever run it to mid either? That's just stupid. And it also only takes 100 dmg to fill up the boost.
So it's only useful on granary? Literally every other map, scouts have good reasons to jump around (get on spire, get on crates, jump around, etc). Double jumping is really important on most maps.