Only downside to Song Brother on a LoM captain tank is the -healing threat, which has the potential to cause agro issues. Either way, by using both, it allows both of you to have Song and Shield up.
From a tank's perspective:
||ICMR is a slight reduction to healing load
Crit will help with threat generation
|ICPR will the LoM tank with power issues
-Healing Threat may cause agro issues
|Strength of Will
||Faster Attack speed = more skills/minute
||-healing costs useful for power convservation
||More threat from increased DPS
||More threat from increased healing
||HoT + PoT Better Support for the HoH
||PoT means LoM power problems vanish
Hopefully that helps.
Maley Oakensage, Captain of Elendilmir
Alas Elendilmir, may you *jingle jangle* forever in the Forgotten West