I take "Master Scout" in every game on Ridiculous/Insane difficulty because without it, you cannot move fast enough to be competitive - i.e. it takes TWO full seasons to kill a bear and loot its lair. At that time, the AI is running with speed 3 out of the door (they get Tireless March for free on high difficulties)
Still, I hate the damn thing. With it, one of the best parts of the game is taken away. Instead of feeling that you are in a hostile world, you could just ignore monsters, and build stables next to bear dens, or cities next to Umberdroths. As a home rule, even on Insane, I still act as if I did not have the immunity - i.e. I clear areas before I settle them, and I make sure my outposts do not oversee monster lairs. But it breaks my immersion.
If it were up to me, I would take away the invisibility to monsters, and only let master scout remove the penalties for traversing hostile terrain. To make things interesting at higher levels, and leave Tarth's AI its strength, I would introduce a spell that would mimic the effect we have now. No school, low cost to cast, and free for Tarth and even all AI at highest levels. Players could get it too, but I would stick it high in the magic tree, maybe as high as Tireless march.
As an alternative to changing "Master Scouts" I would give champions a trait that makes them scouts, and the ability to choose whether they are attacking OR moving-while-attacking. This way the exploration will move a bit faster, and "Master Scout" could be left on the cheese pile.
