No arguments here, Joel, indeed I'm really looking forward to A18's newer systems, and to taking it nice and slow (though probably not till .2 or so will I commit to a longer term game).
I'm just pointing out that many players new to 7Days are likely to automatically see "faster XP" as an untarnished positive, not realising that leveling quickly might actually make things very much harder for them.
The usual game trope is either, harder areas, with higher mobs and better loot, or restarts on higher difficulty levels with harder mobs and better loot. 7Days goes against that grain by "leveling up" (for lack of a better term) the mobs to match, more or less, the players level through the gamestage mechanic, meaning that those that have done so arbitrarily fast, through either rigid focus on high XP activities, or simple XML edits, will actually find themselves under-equipped and unprepared for what they'll face.
Really the only issue I see with that, is that a newbie isn't going to understand that the game will do that, and will, more than likely, try to level up faster than not, not realising the effect it'll have.