Well, this is the first time I witnessed how long "professional" pre-release testing can actually take... and yet, I still see a bunch of new updates for backroute fixes coming up. And that even with such an experienced level designer like you.
That's a little demotivating as far as creation of my own packs is concerned

... as well as for any other more "casual" level creator, I guess.
Is somebody already LPing this pack on YouTube? And on a general level: Are there any LPs of packs which showcase them in a predominantly backroute-fixed state?

Because let's face it: Once somebody has completed a pack, they rarely go back and check whether their replays are still working in the most current version.

The upside for me is: This pack has proven itself way too difficult for me at the moment anyway. So most likely, when I finally get back to it after hopefully having beaten some other, easier packs, it is going to be in a state where most of the backroutes have already been discovered and removed!
