My friend in Colorado brewed a batch of my porter and it tasted a lot different from mine here. He has very hard water while we have very soft water. Conversely, I brewed one of his IPA recipes and had to had a decent amount of gypsum to get a similar hop profile.
We didn't do direct comparisons, but at least in the case of my porter I've brewed it enough that I know exactly how it comes out, so I could easily tell the difference.
Bottled: Atonement Brown Porter