In the pagan world, local custom takes priority. One could regard this as a general principle of pagan social protocol.
If in your valley, you keep Yule in one way, then when I'm visiting you over the Winter Solstice, that's damn well how I'm going to keep Yule too, regardless of how I may celebrate back at home.
Hey, you have the perfect right to be wrong if you want to.
Needless to say, there's a certain amount of tension here with the universal human belief that the Right Way to Do Something Is—of course—the Way That I Do It.
In practice, it's a balancing act. If you tell me that your name is Xfghstk, pronounced “Tom,” I will call you Tom to your face. What I call you behind your back is another matter, and you can't say you weren't asking for it.
To extend this principle of Local Priority, I generally ride with the idea that the local pronunciation is the correct one; still, that horse will take you only so far. When I hear native Midwesterners drawling out Nyaaawlunz, in verbal caricature of some son or daughter of the Crescent City, I cringe. Maybe that's how they say it Down There, boyo, but Up Here at this end of the Mississippi we say New Orleans. That's four syllables, mind you, not three. Dialect is dialect, but affectation, after all, is affectation.
Case in point: Appalachian. North of the Smith and Wesson Line, we say: AppaLAYshun. South of it, AppaLATCHun.
This raises problems for inveterate listeners to National Public Radio such as myself. Unfortunately—NPR being based in DC—this means that the NPR Received Pronunciation is AppaLATCHun.
I confess, I grind my teeth whenever I hear this. (It bothers me in particular when Aaron Copeland's Appalachian Spring gets deformed into AppaLATCHun Spring. Shudder.) From Southrons, I'll accept that pronunciation, since they have their own customs, and probably don't know any better.
When, however, I hear fellow NPR-listening Northrons parroting that pronunciation, I invariably feel the need to intervene.
“In the part of AppaLAYsha that I come from, we say AppaLAYsha,” I admonish.