On this forum the results were 50/50. On a different forum the results were 70%-PB's/30%-80/20's. One of the key findings was that it depends on the guitar. Many respondents us 80/20's on some of their guitars, and use PB's on the others. I should have given the option for "both" as some people didn't vote because that option wasn't available, but noted in comments that they used both.
So, Jersey Tuning, why some local shops don't stock more 80/20's I don't know. It seems that many people continue to use them. Like other products for other stores, if you don't find what you're looking for talk to the manager about bringing the product in. You'd be surprised how often you'll see them being stocked soon afterwards.