Hi, this happened to me once while I still had an HTC Sensation, every rom I flashed didn't boot past the splash screen boot logo, and it had something to do with having s-on instead of s-off in my phone's recovery preventing it from booting other custom OS's.
I found a fix somewhere, which made me understand I didn't need to have S-Off to have a Custom OS, flashed, rather, there was this small trick, booting the phone from the boot.img file with adb instead of rebooting from a custom recovery. This was an HTC Sensation, not a Samsung, Only trying to help:
* Get/Extract the boot.img
file in your custom rom's zip and save it somewhere on your desktop.
* Once you're done flashing the custom rom in recovery, DO NOT reboot from recovery, turn it off by removing its battery and fixing it back, then boot your phone into downloader mode and run these commands.
( path to where you've got your boot.img file )
adb flash boot boot.img
Your phone should now boot the custom Rom fine, like I said, you'll be trying this at your own risk, as this worked for an HTC in a similar situation.
Hope I was able to help.