Photoshop's interface is awful, and the reason you like it is because you're used to it. GIMP should spend absolutely no time in imitating its mistakes.

Of course, we're offering zero evidence that either position is true, just bald assed assertions. That I vastly prefer multi-window is my only evidence.

>People understand Photoshop, and it's the industry standard.

They've been trained to. It's as intuitive to you as the way home from work. It's as intuitive to me as the way to your house from your job.