Stealth increasing with experience

[PvK]

Yep. Makes sense for assassins too. I don't see a problem for leaders, especially if the game uses the lowest stealth rating of the troops under the leader's command. It does not seem to be very hard to counter high stealth Ratings, so I don't see this as being unbalancing, as long as the dev's check the formulas used for detection to make sure there isn't some issue at the high end with certain units.

PvK