"Historically, the Ostwind was an improvement over the Wirbelwind since 20 mm (or less) was considered insufficient for anti-aircraft purposes. (This matched the British experience.) "
Ture this is, howeaver in AH most people have a very hard time hitting with the osty during deflection shoting, the spray and pray potential of the Quad 20mm gun mount on the Wilberwind would defentaly enhance it's hit potential imo, Historical fact and In game reality do not always coincide. Also just a few pings of the 20mm ammo would toast most planes, just like a few pings of 20mm Hispano ammo toast most planes.
"The Wirbelwind predecessor SdKfz 161/3 actually had twin 37 mm cannon, but it didn't have any gun crew protection and could only open fire after lowering to turret sides to form the crew platform, so it was really lacking in mobility."
Their was no Twin 37mm mount produced on the Mobile wagon series, the 37mm mount was a single gun, the same gun as used on the osty( I beleave), and the Quad 20mm mount produced in the mobile wagon sieries was the same as used in the Wilberwind, although in an open mount similar to that shon in the picture.
2cm Flakvierling 38 auf Sfl PzKpfw IV SdKfz 161/3
3,7cm Flak 43 auf Sfl PzKpfw IV SdKfz 161/3( shown Bellow)