If you don't tie the springs to the perches and you droop beyond the free length of the spring, gravity will still be pulling the unsprung weight of the tyre, rim & hub down to the ground, imparting a very small amount of traction. (With the caveat of the spring maybe not seating correctly upon re-compression)
If, however, you tie the springs to the perches, then your stretched spring will be pulling up on the tyre/rim/hub combo, fighting the gravity pulling it down and reducing the tiny bit of traction it would give you. I think that's what Kurt is trying to say, right?
In reality, I don't think think the amount of traction from 'dangling' suspension could be that great anyway so is this difference even relevant? Given this, i'd probably go for tying up the springs in this instance. On my minis, I just had bump stops to stop the suspension trumpets from falling out
Never did get very far in fine suspension tuning on them...
I just had a cuppa by the way
Tom...