Probably just in Strikes and Raids, and Public Events. I'm thinking no more then 2 at a time to support a group of Gobs, Hobs and Herps. The Vex have that relentless march in combat. The Centaur would be like a battering ram to push back a line of Gaurdians. Usually we can just continually back up and keep shooting at a charging enemy. The idea of the Minotaur is to force us to consider a new specific area to engage from. They would also give Public Events like Defending Warsats or Preventing Sacrifices a much needed difficulty spike. Also with the Vex being able to Spawn anywhere (Though now the HIve can do that apparently) the Vex would try to flank you with them. But to keep it balanced their footsteps would be loud when they got close.