Yea, spreading the champion / lord / icon bearer throughout the units available in the formation means 3 invulnerable saves, hurrah!

but means they potential of the formation dips as the casualties come in... the 'eggs in one basket' approach has the advantage that, as long as the unit doesn't get splattered over the games table early on, you have access to all of those abilities whilst that uber unit is still alive.. one of those swings and roundabouts situations I think. Shall have a think about how I want to model these bad boys up... but good to know I can go with either option

(obviously you guys know that, I'm just rambling out loud to myself!!)