I thought I wasn't going to get this mount just because of the rep grind, but then I did a little and realized I could grind it while watching really bad movies on Hulu.
The nice thing is that, as a rep grind, you don't have to wait on RNG to smile on you. For me, it's been a few days of grinding. I did most of Revered in just one day, hitting it as hard as I could, and that's the longest part. (Also, you can get Timbermaw rep at the same time if you do the prerequisite quests to get the drops.)
The hardest part for me was getting through Friendly and into Honored to open up the third quest. There's not much of a flow to the first two quests, but once you have three you can get into a solid farming groove -- run southeast to the Ursas, kill the camp; run south to the giants, kill the giants; run back up to the Ursas and kill what's respawned; run north and kill the bears and chimeras; turn everything in; repeat.
Yes, it takes time. But 2-4 really dedicated Saturdays should get you there. You'll only need patience and dedication and something to entertain you during the mindlessness.