I've done several quests without running into any monsters... In fact, the only time I did spawn any was on a Yew to Britain quest and the mobs spawned within the city limits (just west of the Warrior's Guild (the one south of LB's castle) and a guard appeared and killed one of them.
I'm really hoping we get to test the mobs with proper scaling before this goes live, as what spawned for me would have taken a decent sized group quite a while to kill. 14hp energy bolts using the proper specific-type slayer on a powerful mage was discouraging to say the least. X5 and it just wasn't worth my time. Also, please remember for scaling that the damage disparity between a mage and a dexer is dramatic; dexers may use multiple slayers (weapon, talisman, EoO, Honor) plus multiple weapons/skill specials that put Word of Death to shame in the long run. They can get 300% DI easily, while mages can get ~120 SDI if they spend a lot of gold and sacrifice other stats.
A few mobs of greater dragon type difficulty would probably be powerful enough to be challenging, without making it absurdly difficult. The chances of people repeatedly doing these as a group, in the long term, is low.
