Nosferon: It's definitely too revealing, but not because of location (the concealed
unit maybe in one of many hexes), but because it gives you info about
the unit that you shouldn't have. To have your stats concealed is way
bigger advantage, than hiding your location, imo
I disagree. You can write down a hero's stats and track their growth that way (I did it late game against Southern, just to keep in mind what would work when I finally cornered him), but their location tells you where to go to kill/avoid them.
southern: if you right-click on a message the game pings the hex the message comes from. Thankfully, the levelup comes at the start of the turn, so the concealed hero does have a chance to move away. Also, the message doesn't give you the hero's stats, although it does tell you they levelled up, which I suppose is what you meant anyhow.
Game's over, so I'll mention this:
You can actually track the hero until the message goes away (so for 2-3 turns). Right clicking on the message gives you a ping on the hero's
current location, even if they are concealed or in the fog of war.
I discovered this during Broken Bow, when you happened to level within my vision.
southern: In a game a few months back I ended up with one hasted, concealed, free-movement, 50 movespeed, level 20 (or so) hero, while Bookwyrm had most of the map. I was running around occasionally razing things, and I planned to eventually restart a territory using Animate Town on the ruins.
Eventually Bookwyrm shut it down by using Town Portal to bring an air galley down on top of me.
I had too much stuff for you to be able to restart anywhere, and I was making sure to rebuild razed towns after you left an area. If you ever stopped moving, I'd catch up and kill you, and if you left a city alive, I'd have crushed the restart before you could amass a viable defense. I was rapidly expanding into the last corners of the map while still chasing you.
I did need the Town Portal to finally catch you with something that could kill you, though.