in 98% of cases normal raid can avoid infernals but as boxer you have to do /follow on someone and move whole raid in the same time. So you cant throw any heals because infernals will burn someone untill you are out of infernals' aoe range. No heals at that time and a few heavy hits by the boss (especially in phase 2 with fast attacks) will more likely cause you to wipe.
I can show you positioning with zero movement once you pull. You fight int he exact same spot from 100% to 0% no running from infernals. No door exploit, just a very specific positioning thats possible in at least two spots on the balcony.

True, not to mention it would be a tough fight with only 2 healers for a non-boxed raid. Especially without the massive druid dots to keep ticking while repositioning.
In the build I suggested you have three healers - a holy prot pally, a shadow priest and a holy priest. We generally get through with only 2 anyhow so having the 3rd is just gravy.

As far as maiden positioning goes, you spread out 1 character between each pillar... you face them all straight at the maiden, and bind a key to move them all in at the same time... you charge in with the warrior with the paladin on /autofollow, then press the run-boxed-toons-forward key and hold it til they are all in position between the pillars. With the build I suggested you have 3 dispellers, so put the pally behind the warrior tanking, and put the other two dispellers at his 10 and 2 o'clock positions. The last member stands at max range behind the paladin, the pally can dispel them, dispel left right and center... the priests can cover the other 2/3rds of the raid.

I figure it takes you less time to position 10 by yourself than it would 10 in a raid that way.