boolean modifier / spacial set math / general modeling question

Hi-- I have an example file here: http://www.pasteall.org/blend/21611 (making it for 3d printing).

Essentially I’m trying to subtract one mesh from another. I’ve tried using the boolean modifier tool to get the difference between them, but it either crashes blender (and no matter what it takes forever) or it doesn’t give the desired result. It ALMOST gives what I want if I use the subdivision subsurface modifier and then subtract the text block from the iphone case, but it fails because blender doesn’t infer which sections of the text to cut out and which to leave behind.

Like, part of the “e” gets doesn’t get cut out, because the inside section of the e would be left behind, so it just cuts that out instead.

I feel like this sort of model modification should be easier, is there not a better way to cut objects out of other objects?

Thanks.