Does Reverb work on iPhone Duo?

Yes. Reverb is updated for iPhone Duo and uses the full inner display. Owners report it fills the inner display.

Is Reverb letterboxed on iPhone Duo?

No. Reverb fills the inner display.

Name: Reverb: Buy & Sell Music Gear
Author: Reverb.com

Reverb.comShopping

On iPhone Duo

Reverb fills the inner screen and adapts when you fold.

Owners report it fills the inner display.

1 report from people using iPhone Duo

Most reports are from version 7.19.0.