Bought a Droid 4 a while ago (they are dirt cheap and the keyboard seems to be nice) but never used it.
This port sparked my interest though so rooted the device and installed safestrap yesterday.

After installing Sailfish and rebooting the screen turned black (lit) and didn't show any error message.
I didn't turn it off this night (not knowing how long it takes to boot the first time) but this morning still a black screen.

Wiped the phone and tried again. Same result.
Wiped the phone and only installed CM11 and booted CM11 - that worked fine.
I used ROM slot 'stock'

Maybe I am missing one obvious step - I am not very experienced in flashing custom roms for Android phones and never used safestrap before.