I think where companies source their briar matters a great deal, aside from workmanship. I've had great luck with Peterson, almost all have been good smokers, clean tasting, and the one that wasn't finally broke-in. Last I heard they get their briar from Spain, and from Corsica for the high-grades.
But I've had bad luck with Rossi, the ones I tried smoked bitter for me, I couldn't smoke Virginias in them. I use them now for burley blends that are a little too sweet, because they counter the sweetness. I've had the Rossi's for years now, so aging of briar apparently isn't a factor there.
But I believe Rossi is made by Savinelli, as I also believe Stanwell is, and I've been happy with my Italian-made Stanwells. So go figure. The Stanwell bowl coating was much better than the Rossi. So if they're both made by Savinelli, do they use the same briar source for both? I don't know.