Pfft. Shadows are amazing. If your guild can't down a boss with any (reasonable) group composition, then they have a long ways to go. We run with a Gunslinger and he rarely pops his bubble so any "buffs" he brings to the raid is minimal.
If your struggling to get included as a Shadow DPS, you could try tanking. They are quite amazing.
They replaced me with a sage, and proceeded to down the boss thanks to the offheals.