Concur. It's not quite as widespread - what I've seen is that even quite a few non-natives tend to adopt "needs washed" after living in the region for long enough, but I don't hear yinz used unconsciously from people not born in the region. But there's plenty of yinz - and the city embraces its yinz-ness.
I always heard it round dahntahn. Norseide and Souside, mostly. In the Nordills, it wasn't as common, but my gramma sed things like worsh and spigot but she grew up dahn Etna an aht.
My home town takes a lot of its accent from Baltimore, though it's still over two hours away. I never got used to saying "you'ns". There is a definite glottal stop in the middle. Annoying.