Great thread, thanks for starting it.
I'm not a pro arb, just learning for the last 2 or 3 years how to climb by reading and watching everything I can on the internet. Because I only climb for friends and family, mostly pruning deadwood or hazardous branches, I don't usually feel as though I'm being pushed for speed. My prime concern is to come back in one piece, no injuries. As a result, I don't really do limbwalks in which it is possible to take a huge swing. Call me cowardly. I use two ropes, double SRT. I'll have my main line with a really high primary suspension point, and a second one that I can use to pull myself out to the end of the limb that I want to walk out onto.
I guess I just always figured that it would be really easy to have my foot slip off of the branch I'm trying to walk out onto, and that if I only had one rope, I could take a hard thirty foot swing at high speed right into the main trunk of the tree, seriously banging myself up. So instead, with two ropes, what happens when my foot slips is that I do take a swing, but it's just back and forth over or right next to the spot on the limb I just slipped off of.
So it's like a kid's swing, only with much longer ropes. I hope I'm being clear here. The path of my swing is perpendicular to the branch I'm trying to walk out on. By way of overkill, sometimes I even use a third, shorter rope with a separate climbing system on it, too.
My idea is that with attachments in three different directions, if I tend slack all of the time, it's just a matter of moving in the desired direction of travel, with almost no possibility ever of taking an uncontrolled swing.
I have read some arborist's writings about the strategic use of big, deliberate swings, for speed of covering distance in the crown. Being good at that would be really efficient and powerful, but it probably takes a lot of practice to get good at, and you have to be willing to risk injury, I'd imagine.
In the right circumstance, it might be possible to practice swings fairly safely. An uncontrolled, accidental swing could have life changing consequences, which is why I act like such a chicken.