Used to charm solo with these guys, a little hard, but doable. Easier with a ranger/druid. Used one for pet, depending on random roll generator, charm would generally last the full 8 minutes, using Boltrans. 1 pet would last 3 - 4 mobs, then I would break charm and grab a new pet. Could stay for hours up there.
That was with a chanter from 58-63. Experience sucks at 63. Got 1% - 5 kills.
Had a 60 enchanter with me in BF and he would keep one charmed as a pet to help with dps. Had to recast 1-2 times a fight but yes it is possible to charm these guys.
Is this going to be another Velious type expansion where you have to pick a side? I killed a ton of these things without even thinking about faction. Hope I can reverse it if needed.