Is cleaning all the heads that great of an idea? Doesn't placing new heads cause more damage to the rock? Lost in America is hardly a clip up.... at least when we did it in a push it wasn't. Besides, the A4 pitch doesn't have many if any fixed heads...just good ole fashioned knife blades and beaks.
If heads are such a bad idea they should have drilled bolts in the first place, or we should be drilling bolts now.
I've probably removed more heads, deadheads and heads with broken wires than anyone in the past 10 years and I can tell you that no, removing the heads with a butterknife, does not damage the rock anymore that the original placement of the head does.
Okay, you can all breath easier. Both of my big wall mentors recommended taking out deadheads, heads with broken wires and heads I can avoid by other means, but otherwise leaving the fixed heads alone.