@Mod Mat K
As an Old School player and a level 3 skiller, I find myself in a somewhat, "grey area" with this idea. When I first glanced at it, I was beyond excited to do some roof top running. I could also imagine more shortcuts added. (Example: Climbing to the top of the Varrock Museum and finding a birds nest.) Rewards, of course, matching the level it requires to use the shortcut to reach them. It would be a pretty nice but small addition to the skill.
For xp rates.. Touchy for everyone to think about it but, I would hate for this to turn the Agility cape on 07 into the Runecrafting cape on RS3. In other words, making it one of the "easier" capes to achieve. Maybe set each course's rate slightly lower or the same as the courses we have now for lower levels. For 85-99, perhaps raise it a bit to reward those players who have spent the time to gain such levels.
Its really a bittersweet idea to me but, if done correctly, it shouldn't impact the scarcity of the awe-inspiring Agility cape. My other concern, is that if it does reach the goal to be added into the game, please make sure it is available for all players/accounts/pures/etc. Choosing the non-combat way is a sacrifice I've chosen but, myself and plenty others wouldn't want to be left out of something that could be so big. I hope this doesn't impact other skills as well. For now, I have no vote on this. I can only hope everything works out.
Keep it nostalgic.
-Agilities