I (being relatively new to all this) was really parnoid about airing down (popping off the bead, "flat tire" etc...).
I took baby steps at Broken Arrow and aired down to 20 PSI and didn't really notice a difference, so I didn't think it was that big of a deal.
On Judgement Day I took the plunge and aired down to 11 - 12 PSI and I will never ride another trail again without airing down that low. The ride was better, my grip was better, looking at some of the rocks I'm pretty sure I would have split a tire if I had been fully aired up and there was no "give" in the tire due to being under-inflated.
Typically, on the road, I run 30 PSI and it's great for highway driving, but when I get to air down, it's 11 or 12 PSI for me from now on.
(Thanks Sc00by for encouraging me to go that low... also thanks to the dude who gave me the automatic airdown that dropped me to 11 PSI without me knowing it went that low!!!)
Sc00by's C02 set up was perfect for airing back up and is now on my list of things to do to my Jeep.