Hello,
I have been using/testing this new Classes.txt file. I have modified the experience to have a smoother level-up effect and increased the number of levels that are user-defined to 22.
You will have to start new characters, but I think in the long run, this is a good thing. (it may be safe to import an old character, but I haven't tried this yet!) leveling after level 22 is the same as before (+200,000xp/level)
Here is the file..
Classes.zip
Try it out and let me know what you think. (Personally, I don't think I'll ever go back to the old xp system.)
Cheers!