This does seem a bit unnecessarily confusing. I would encourage you to take advantage of all the things you can do to make the beam phase much simpler. You want to minimize switches if possible. They have some risk of going wrong. Also, people will die. The more people you have assigned to hold a beam, the less backups you have. Make sure your strategy does no fall apart if you lose a person or two.
In particular:
- Healers are okay for the green beam, but rogues and DPS warriors are way better. Rogues and warriors get only an advantage from it and no disadvantage. (They get stacking lower energy/rage costs for all their abilities.) Thus one of them can hold the green beam for an entire phase and put out obscene damage in the process. 2 people total and the green beam is covered for the fight. If a healer gets low on mana they can "tap" the green beam for a second, but with the tank needing no healing in the red beam, mana is not usually an issue.
- People can always hold a beam for 30+ stacks. Using more than 2 people per beam per beam phase (4 total for a beam) is just making the fight more complex. If you use 2 people per phase, they can always take the same spot again on even/odd beam phases. Ie. the tank for the fist half of red phase #1 also does the first half of red phase #3, 5, etc.
- Ideally only spell casters should take the blue beam. They get an advantage from it and everyone gets a disadvantage. A decently geared warlock can hold the blue beam for the entire beam phase using Life Drain. They take steadily more damage but they drain steadily more life.
Thus just to throw out a quick example:
Red Beam: Fiadfiel, Tanriel (odd phases) / Voldir, Kalynn (even phases)
Green Beam: Voldir (odd phases) / Taius (even phases)
Blue Beam: Laela (odd phases) / Kaadan (even phases)
In any case, its my experience that the banish phase is when the fight is won or lost.