quasi religious?

Very much so! If my church started par-boiling brats for the summer
festival, I would have to convert to some other religion! My experience is,
at least in S.E. Wisconsin, there is a line at about Port Washington, North
of that line...no boil, South of the line they boil the crap out of the poor
brat before they hit the fryer.

I would have to say that we here in the Sheboygan area take our bratwurst
seriously, very seriously. I am also the President of the local Homebrew
club (The Sheboygan Sudzzers) we have discussed this very topic at length
and we all agree, leave the par-boiling to the armatures. As part of the
Club's annual Oktoberfest celebration we have our own bratwurst recipe with
Rhinelander Bock and tripple garlic. Damn good sausage, but the wife stays
away from me for a few days after that brat fry.

Boil if you must, but please in the name of all things good, no yellow
mustard!