@Hyperspeed
Well, regardless of the polar holes, the ozone layer is definately thinning globally if you look at the entire set of available data.
The evidence for CFC damage is pretty damning. The problem is that CFCs are extremely stable in the lower atmosphere, once released they will survive for a long long time. One 'debunking' argument is that they are denser than atmospheric gases and therefore wouldn't find their way up as high as the ozone. This is, of course, utter bilge. The atmosphere is not generally "sorted" by molecular weight, natural turbulence and diffusion are more than enough to get them up into the stratosphere.
Once they get there, the UV and particle radiation is enough to break the bonds between the carbon and chlorine atoms. This is where the problem starts. The chlorine atom released breaks down ozone *catalytically*. Therefore, one chlorine atom can break down any number of ozone molecules it comes into contact with. In other words, it only takes a small amount of CFC to reach the ozone layer, be decomposed to do a lot of damage.
There are natural sources of ozone depleting chlorine, such as volcanos etc, however they generally belch out hydrogen chloride (rather than chlorocarbons), which usually end up in clouds and getting rained back to earth. Also, hydrogen chloride doesnt exactly dissociate as readily, nor in the same way as a chloro carbon bond (you are much more likely to see H+ / Cl- than H / Cl).
I suspect the holes at the poles would be at least partially the result of their extended periods in the dark, during which time the ozone would decompose back to molecular oxygen. Perhaps some fluid dynamic behaviour of the atmosphere concentrates ozone depleting pollutants close to the poles, frankly I have no idea, but again if that is the case, I'd expect a larger depletion in the northern hemisphere, were most of CFC producing people live.
Methane and other gases would probably be oxidised by ozone in the presence of strong UV (thereby depleting it) but this reaction would not be catalytic - the methane would be converted to compounds that would, eventually, not be capable of further reacting with more ozone. This is quite a contrast to your chlorocarbon case where the liberated chlorine atom can destroy as many ozone molecules as it can come into contact with before eventually being lost from the atmosphere or captured in some other way.
