This is exactly what I had hoped for. There is no reason why I should not have permalinks without nesting if that's the way I want them. having mysite.tld/maincategory/postname is perfect!
However I've read that the server can experience some serious performance issues choosing this or tag/postname, etc. I should have about 800 articles on my site by end of year, perhaps more. Wondering if there was any notes on performance.
In addition, is there an easier way to mass assign to posts? I guess there isn't a way except using mysql queries at the moment to say "all posts in category X should only use category X as the permalink." Hoping this might be on the agenda or even possible.
Great work to keep this standardized. Many thanks.