My guild is at 4/5 MH and 5/9 BT. I am the guild leader. My main is a tankadin. I box four shamans, focussing on PvP. 2/5 Brutal now, everything else I could buy for honor.

My 2 cents on this:

I took two of my shaman to Archimonde yesterday. The raid was led by the deputy guild master. The reasoning was that I could up the total amount of shaman in the raid to 5 and we could have a tremor totem for each group. I stuck my chars between the two groups I had to cover and it went reasonably well, once people stopped standing on top of me sharing their air bursts. I would not have gone for this though if we had enough people with sufficient gear and a stable connection available on that night.

I regularly ran Kara the last few weeks for the badges needed for the pvp cloak and the battlemaster trinket. Using both my tankadin as only tank on the run and my shaman as primary dps, that leaves five spots for 2-3 healers are more dps. Depending on the week, there have been dps that were stronger than my shaman or well, not stronger. =] The only bosses in Kara that I have not repeatedly and reliably killed while five-boxing are the Netherspite and the servant's quarter random boss, which we do not usually go for.

That being said, my point is: on any serious raid, I personally do not want to box. On farming raids that I outgear anyway I see no reason not to box. Feel free to call me a wimp. =]