I did the fight with a Holy Paladin. You both need to be tank healing, as they take a lot of damage. Also a quick shield on someone low buys you time that holy cannot give. PS, and PI (I gift to a DPS), are also very useful this phase. I have played holy with minimal mana issues, you just are able to over extend yourself if needed as disc. Heartsong is a waste if you are playing properly.
Yoply kite u should not need B&S P4. Simthe orb out of the group for a couple seconds, have it knocked back. Rinse and repeat until you are kiting it into the patch to kill it. You should only be getting one meteor in P4 anyway.
In regards to if the phase is easy...well, I guess if demanding perfect play from all members is easy then sure! Its a cake walk!
Please bare in mind that I love holy. I used to main spec it. Its just not optimal for Firelands unfortunately. Best of luck on a kill