G-R-G-R... is fine. The breath from the blue head is a lot easier to deal with than the green/red heads, so you can deal with the extra attack speed. Even with a fully stacked blue head I was more scared to tank the green one. This was tanking in a pug on my 495 Brewmaster.
The OP has already clarified, but to repeat: he is NOT talking about the blue stacks that build on the tank, he's talking about the Hydra Frenzy stacks that build on the head you choose "not" to kill with each pair of heads. Tank swapping isn't the topic here, it's the kill order of the heads - and no matter what order you do tank swapping is involved.
he's talking about the Hydra Frenzy stacks that build on the head you choose "not" to kill with each pair of heads.
The fact that nobody knew what he was talking about until he clarified should indicate to the OP how serious that mechanic is to the fight. Rule 25 and 26 of the Internet have been upheld in this thread.
Just a quick update, it turns out that I was seriously overestimating the difficulty of the fight. We went in and tried GRGRBRG, and got almost instagibbed when nobody paid any attention to the first frost beam. The heals and tank agreed that Blue wasn't meleeing for too much, so we decided to leave the blue alone and just go GRGRGRG. Second pull kill...
We've been doing a B > R > B > R > G > B > R in 10 man with three healers, and haven't been having any problems with tank deaths (Brewmaster/Warrior) other than a miscommunication or two. As long as your healers let tanks/other healers know when they're out of range of their assignment from kiting blue, it's not really an issue until the last head. We found that with our (slightly) undergeared healers, just dealing with red and blue and using them to clean each other up worked well, saved a lot on mana too, which is mostly burned in the last two heads. Requires communication to properly get rid of ice patches with cinders so your healers don't murder dps by dispelling way early and stranding them unexpectedly in ice.
Granted we have two mages and two druids (speccing displacer beast) so keeping ice patches on top of each other and moving out of fire is easy for us. YMMV.
Focusing Blue and Red is a lot (LOT) less raid damage so long as you have competent movement/positioning/communication. DPS check is negligible anymore so a little bit of movement won't kill your tanks. Has potential to get hairy on the last few heads but what kill order doesn't?