Just as an update to this...

The mixed team is at level 51 now. It does work alright, but I have to say the warlock is massively underwhelming. This might be due to my macro-fu failing, but still...

Priest has been smite spamming for healing since level 29, it did work better, but it is also tapering off now and I find myself click-healing via video-fx more and more.

So far, all RDF dungeons have been doable up to this point, but I found out the hard way that if a toon dies and the rest of your group kills the final boss, the dead toon does't get experience and gets left one whole level behind... Silly/small stuff and I corrected it with quests later, but it was annoying to have them that far off one another.

I'll take this team to 80-81 then start a all-orc warrior+4shamans. Or maybe it'll be time to get the DKs started.