I remember reading somewhere the the Jersey line was used in the tour and in international productions such as the original West End one. This was because international audiences would know what Jersey/New Jersey is but people that don't live in NY might not get the Hicksville joke because a lot of those people don't even know what Hicksville is.
I remember reading that Larson said that Maureen was from Hicksville only after finding out that Menzel herself was from Long Island. I don't think that was the original line Larson came up with.
"If you try to shag my husband while I am still alive, I will shove the art of motorcycle maintenance up your rancid little Cu**. That's a good dear"
Tom Stoppard's Rock N Roll