Ok, here is empirical data on Battlemaster, which i recorded with one of our tanks having the enchant:
http://www.lossendil.com/wws/?report=f2yoezjaz4axo&a=25

DPS time (combat time) = 70 min
Battlenaster procs: 52 (260 recorded by combatlog because in a group if 5 it procs/heals for every member)
Average heal: 257
Proc/min: 0.7 (which I think was also confirmed by other people using ProcWatch somewhere in this thread) = 7 procs in 600 sec = 1 proc every 85 sec.
Overheal 43% (this just happens to be the overheal for this fight, first 4 bosses in KZ)

So the healing component of Battlemaster:
257HP/85sec=3HPS if heals just the tank (0 if tank is at full health)
257HP*5members/85sec=15HPS is heals everyone in the group
Average for the raid (43%overheal) = 8.55HPS

the threat component:
HPS*(heal threat modifier)*(defence stance +defiance modifier)*(partymembers healed)=TPS (threat per sec)
0 if everyone is at full health
3HPS*0.5*1.45*1=2.175TPS - for one person healed
3HPS*0.5*1.45*5=10.875TPS - for 5 people healed
Raid average (43%overheal) = 6.2TPS

But in absolute numbers, with the healers outputting around 580-680HPS, and warriors 500-700TPS it not quite overpowered. And it does not scale with the gear where as Mongoose and Agility enchants do.

Please correct me if I have done any miscalculations or misread the log.