I have a lvl 70 feral druid tank in some T6, and a lvl 70 shadow priest twink, along with my lvl 29 pal/4priest team. A Pally tank is the way to go when 5 boxing. concecrate is pretty much all you need to hold agro and it's alot easier to tank that way than to swipe tank. Swipe tanking on a druid is fine if you are going to single target and your just swipeing to keep the agro on you and not your healer, but if your going to chain lightning or arcane explosion spam you will rip the agro right off the druid. I've done a heroic shattered halls on both druid tanking and on my shadow priest with a pally tanking. Pallys hold aoe agro like no one else can. I Love my druid and we can tank like mad, but for anything that you would consider 5-boxing without any CC the pally is a better choice hands down.