It is a HUGE penalty on a Mage to lose his pet if he becomes charmed, compared to all other classes who emerge virtually unscathed. It is a no brainer not to take Mages anywhere ever to any encounters.
I suggest therefore that Mages be made immune to being born in the first place
Susvains solution sounds more reasonable - nerf pet dps a tad, boost spell dps a tad to make up for it, call it a day.