Pre-25 I've killed more with a transmuter than I have a druid. Druids really don't become "powerful" until the mid to upper 20's since one pincer/cranial or any reliable non-traditional lagging maneuver can instantly wipe you off the board. If you have a high xp penalty, your druid has to be more picky about who it fights than a mage. But on the brighter side, at least they don't have to worry about giant bashers.

At level 23 a mage can have Aura and Shield and combined with their other spells that makes them much more survivable than your standard druid vs warriors. The only power a druid has that a mage doesn't is the hit and run. They can hit, get beat up, run away, and heal and try to whittle them down. But in the end you only end up killing the ones that a mage would have totally washed off the board without running.