Our strat and methodology exactly. Yes, this fight did get a bit harder in 2.0, mostly on the healers. We usually have one DPS pause momentarily between cores to lay down an AoE on any adds that are in the middle...but only momentarily. We don't fail any phase, have a DPS in the middle of orange with a healer clicking. From yellow on, it pretty much takes both healers working full time to deal with the incoming damage.
Yes, yellow is usually when our 2nd healer starts helping out to heal. However our last time in there, we didn't kill him cause was teaching someone new to the fight, but my 2nd healer did very little healing. I didn't know this till after the fight when looked at the parse. We wiped in 2nd phase cause someone didn't get in color circle, was close to half way through phase and I wasn't having to much trouble with only light heals from the 2nd healer. I was close 900k healing while other healer was around 150k but he had also put out close to 400k damage at full heal spec. That's why I mentioned about may be trying my 2nd healer as a hybrid to put out more dps but still be able to throw decent heals to help me out.
I made sure to mention twice in my post that in order to use our strat exactly you need a Very
strong main healer. I have not tried it this way with out me being the main healer as a scoundrel...a lot easier for scoundrels to be able to throw hots on dps to keep them up while still being able to focus the majority of our heals to the tanks that need it most. I am not sure if other classes can do it with out significantly more help from the 2nd healer. When I was the one that was mainly dpsing during blue/orange/purple...I would drop back to help heal cause usually the other healer gets over whelmed a bit while champs are up.
This big key to mainly solo healing it is the timing of your heals with the healing debuff on tanks. Coordinate with the tank if they get a double debuff that they may need to use a cool down until you can get a full heal on them.
I wouldn't advise trying to solo heal unless your healer is decently geared as well. I am far from bis. I have full 69's with few mods/enhancement still to min/max and Verpine implants, bracers, offhand. I am planning to drop my crit/surge a bit to get some more alacrity to be able to keep 2 stacks of my hots on all 8 during phase 2 and have a little more time to throw a couple casts on the tanks before I have to renew my hots.
Edit: Something else I thought I should mention. If you do try to use our strat and mainly solo heal, your main healer should be on blue in order to get their color sphere right away so don't have to worry about it during the fight.
2nd Edit: Here is a video of the way we used to do it pre 2.0 with me mainly dpsing during cores had a sage main healing. We did loose a tank part way though cause I didn't drop back to help heal soon enough.