Looks good.
One feature request if it's not a huge amount of work.
I'd like the ability to "exclude" or "blacklist" G1 from the auto-arrange.
(Or in any case a group you'll give us.. it could be G8 or any of the least used in current raids)
Reason for that is a group is occasionally setup as "utility".
Where utility = stacking it for melee dps, or stacking it for tank threat,
or stacking it for resistances (think hunter + paladin/shaman for frost/nature tanks on hydross).
So the auto-arrange logic would "skip" raid members in the excluded group.
If it's too much trouble, forget about it... you give us the ability to create our own templates,
it would just mean making per encounter-template on occasion.
Thanks again for sharing your work.