Players almost universally hate Dungeon Alert. It is a contrived mechanic, meant to penalize people who 'zerg' through a majority of the content, so that they can complete the adventure in short order, against the desire of the people who designed it.
Simply put: Dungeon Alert is the result of poor design and implementation.
Instead, if you wish to penalize zergers, apply a flag to alerted monsters which decreases the experience gained in the dungeon. For every mob above 6 (or 8 or whatever number is decided on) that is flagged as alerted, apply a 5% stacking penalty to earned experience. This penalty is reduced for each alerted mob that is killed. I suggest making the mob number before penalty a parameter which could be set by the dungeon designer.
I believe this solution would discourage most people from zerging through dungeons for experience.