Most of the simpler ROMs rely on Samsung releasing the FW, and then they switch out what they want. It is a case of getting all the drivers etc working correctly on the new Android version. I do hope Cyanogen or someone releases it, but its been almost a year and I havent seen anything stable yet. We will probably have 4.5 or 5.0 upon us soon.
I dont think there is a reason to buy a samsung device (anymore), in the past there was. The only advantage maybe external sdcard, better camera or removable battery.