I'd really not worry about being anything but full shadow until you hit 65+. Before then, you can just outlevel the dungeons if things are difficult. We tend to be bipolar when it comes to capabilities on elite encounters (either we wipe the floor with the mobs or they wipe the floor with us).

When we're doing bosses or tougher elites, what I'll usually do is let him go in and pull aggro with frisbee of doom, then I'll drop the following order of spells:

renew the MT
VT
VE
SW:P
flay
renew the MT again
VT
VE
flay
flay
VT
renew the MT again
VE
SW:P
flay
flay
etc...

That usually gets us through most anything. If things get ugly, I'll usually add a flash heal x4 on the MT right before refreshing renew. I'll try and remember to upload some of our boss vids this weekend.