I don't raid or solo, but sham might do decent dps with the poison/disease dots that trigger a second version if they last over a minute? Kind of like a necro, they need the mob to survive awhile to really get their dps number up.
In EoK T1 with a 6-box, nothing but giants lasts beyond 30 seconds. I haven't done parsing, but I like putting them in a melee heavy group and having them buff with Lions (13k dd proc) then just lob spears/short dots. Still I think they are bottom tier DPS for group stuff.