I would say it only matters if you are attempting to make a brew as close as possible to a recipe. There will be differences. But then again there would be some difference year to year. Especially with the hops.
I don't worry about it. But then again, these days, I am creating my own recipes so I have nothing to compare my beer to.
Yeah, this is the same for me. It depends on the beer I'm brewing. If I'm doing a regional style of beer (like a bohemian pilsner, or something straight up Belgian) or an historical beer (like an 1860's British Porter - like a commercial clone from "
Shut up about Barclay Perkins" , then yeah, I might go for the grain specific to that used in that region.... or as close as I can get to it, but I don't sweat it if I can't find it.
But with my "generic" everyday drinking beers, like a house IPA, I'll use whatever grain... usually whatever generic base 2-row might be the cheapest at my LHBS...
It also depends (if you're don't doing online shopping) on where you buy your stuff at. My main LHBS was one of the first homebrewshops to open in Michigan, it's been there forever, is huge, and has every grain imaginable in bulk, including regional varieties of all the malts, so I rarely ever have a problem with sourcing specifics... but I've also shopped at homebrewshops that just have one maltser malts...usually not even in bulk... so then it's just you get what you get.
Yeast and hops I think I pay more attention to regionality/style closeness to.
So for me it varies from beer to beer.. some situations, yes, it matters to me.. and in other beers notsomuch.