This paper has a much more negative slant on Montreal. It argues:
Firstly, while it is agreed that CFC's affect the ozone layer, the impact is so small, apart from Antarctica, that it is hard to distinguish from natural fluctuations.
Secondly, what's of concern isn't so much ozone, but increased UV-B radiation, and again there is little evidence of much of a trend.
And most importantly, UV-B radiation strongly depends on latitude. Thus even if there were a 10% increase in UV-B due to ozone depletion, this would represent the equivalent of moving 100 km closer to the equator.
While I think that the issue was grossly overhyped, and that skin cancer incidence clearly has a lot more to do with excessive sunbathing by Brits vacationing in Spain than with CFC's, and while I am personally unconvinced about the cost effectiveness of Montreal,
it's still a minor issue compared with climate change. Montreal required different refrigerants to be utilised, and even on worst case cost estimates, had only a small economic impact.
In the case of climate change, we are talking about changing the world's energy systems and/or major behavioural changes.
There is a nice map showing how UV-B radiation varies over the globe. It's roughly a factor 50 between the poles and the equator.
While there are no good records for UV-B radiation trends, there are for ozone. These indicate a 4-5% decline between 35-60 degrees latitude (most of Europe and the US), and no decline over the tropics.
So, the decline to date over Europe and the US seems to be equivalent to moving South by around 50 km, and the tropics, which have by far the highest levels (and where according to another reference 30% of UV-B light gets to ground) have seen no change.