If you should ever decide to try carrying concealed in an ankle holster, do be certain to first obtain some sort of washable pad to wear between the holster and your flesh. I don't possess the eloquence to fully describe the sensation of standing in a checkout line in a busy store (ie: lots of people around) while a 3 lb-fully-loaded airweight revolver steadily works to turn one's ankle into a perfect circle. Through the force of friction alone. Even while one stands perfectly still.
Trust me, this is an experience to be missed if at all possible.
Other than that, I think I like this form of carry whenever I'm not inclined to wear anything more sturdy then a pair of sweat pants. Which would be most of the time.
Maybe if these NASA science types are right and we get some global cooling going, I might break down and buy a decent shoulder rig.