The one piece is all about styling - "no center bar to obstruct your view" appears in the ads. Most of us with two piece 'shields never knew we were "obstructed" until we read the ads, but who knows?
Few people think about replacing windshields, and if they did, they would probably say "that's why I have insurance".
Like you, I've had two "halves" replaced in my travels. Last one was $1200. Sure glad I have zero deductible on windshield coverage!
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL