I'll agree to disagree. BTW, my point about healing word healing more was in reference to a single target. I should have been more specific.
EDIT: And I totally forgot to mention that Healer's Mercy is a Standard Action. Healing Word is a minor.
Yup, Healer's Mercy is a Standard Action. So is the Battle Standard. Your point?
You seem to not see the forest for the trees here.
Yes, the Battle Standard combined with the Healer’s Brooch will double the healing of the Battle Standard.
And yes, the Battle Standard could do a lot of healing. Without other healing powers, that's a max 2 healing words + 5 Second Winds = 7 * 5 PCs = 35 extra points of healing by itself, 70 extra points with the Brooch. In a group of 5 4th level PCs, that's nearly half of their total hit points.
It can heal even more in a really nasty fight with other healing being thrown around. But typically, not everyone uses their Second Wind in a fight. For that to occur, it has to be the Fight of the Century. With that much healing in a group, most players do not use their Second Winds most encounters, they are too busy attacking. They only all use their Second Winds in really serious encounters where the Cleric cannot heal them for one reason or another.
You were claiming that a downside of Healer's Mercy was that everyone had to be within 5 of the Cleric. A greater downside applies to the Battle Standard since everyone has to be within 5 of the Standard for the ENTIRE encounter for all of that extra healing that you are concerned about.
That's much more unlikely than being within 5 for a single round, plus the Standard might not be standing upright in a square for an entire encounter (i.e. PCs might gain healing before the Standard is used, or a foe might take the Standard out of the ground, or the Cleric might not use the Standard at all since its healing is slow and gradual compared to many heal options that are faster, the DM dice could get hot and he has to heal and heal NOW).
You are concerned about these two items being used together. It is a valid concern. I think they are very potent together, but not necessarily broken. The healing is gradual and enemies can do something about it.
Healer's Mercy is a greater concern. I've seen it in my PBP game heal 104 points in a single round. That's a much bigger concern than healing 70 points over an entire encounter assuming everyone uses their Second Wind.
Both are out of wack, but the enemies can do something about the Battle Standard. They cannot do much of anything about Healer's Mercy except watch the Cleric push the reset button on the entire encounter.