Thanks for your feedback. I like the idea of moving forward into the next version of each class.
Regarding the upgrade Popup Blocker, it will not apply to new content of the game to be released later.
If you enjoy the game so far, please consider nominating/voting for me for the Reddit 2024 competition:
https://www.reddit.com/r/incremental_games/comments/1hinspw/best_of_2024_awards/