Think of pack like this: An MX bike going through a series of whoops-like in SX.
The bike hitting the 1st one will rebound fully and be ready for the next if it has little to no pack, but if it "packs" it wont rebound to full length fast enough, and will hit the next bump @ say 3/4 travel, and so on until it can't fully absorb the bump and usually donkey kicks your backside over the bars..
Great thread, and has been a fun read. I tried this method last weekend , and I unfortunately can see "it" with my eyes, unless my springs are that close already, I couldn't notice a difference front to rear..