Better sprinting has been updated to 1.4! Also I'm going to work on a new version in a few mins, thx to setosorcerer's idea download in the OP, if you find any bugs, tell me though there should be none, I've tested everything ;).
I think a really nice feature for this would be the ability to configure your ascend and descend keys for flying. I like using C to toggle sneak and holding shift to sprint like in some FPS games. But I don't like using C to descend, especially as a toggle. I currently have Control set as my sneak (hold) key as a workaround, but I'd much prefer to set shift as my descend and my sprint key at the same time.
Hey, this mod is in my Top 5 MineCraft Mods for 1.4.2!
I have linked a annotation to this mod in the video, along with the other ones if you don't want to watch the whole video.
@OP, if you want, you could embed it in the OP, but that's up to you since it's not strictly on this mod.