Hey Florian,
#53 is our favorite so far! I actually blurted out, out loud, "Now we're getting somehwere!" :)
The problem with it, though, is that Apple will crop the corners, making them round--which will remove the corner tabs! Unfortunately we have no control over this...
#52 is also great-- we like that the curve makes it seem like the design is on paper.
The ink drop in #56 & #57 isn't really working for us. Makes it seem like app is about a printer (like for business cards and letterhead)--rather than photographs--since photographs don't use ink.
Not sure what's going on with #55 -- it just looks like it's cropped weirdly.
So, having said all that... any way you can adapt #53 to make it work with rounded corners?
Thanks!