I think we should limit stealth to ten seconds for Spies and 5 seconds for PEs.
It shouldnt be used as a get out of jail free card. It should be used as a defensive measure only. It gets you out of a tight spot and allows you a little breathing room when you get jumped.
APUs dont get stealth and have the most similar defence to the spy.
It should not be used as a tool that people rely on to hide and win op fights as it currently is.
Stealth whoring and safezone hugging are the two things that are killing real pvp.
As there is currently a lack of pvp outside of Op fights I have noticed that this problem has become all the more emphasised. Everyone is doing it. It just sucks the life out of the game.