I think the image will be ported, but the big incentive is not having the locked bootloader. I don't know if Samsung T-Mobile and ATT lock them (i think they don't), even Sprint doesn't, but Verizon is very nasty when it comes to that. They actually pushed out an OTA update to the Note 2 to re-lock the boot loaders - risking bricking consumer devices. From what I read, Verizon was the only one who did that.
Anyway, you are paying for Samsung to stay away from the bootloader on YOUR device...that you paid for...
The Google Edition S4 is the only way to go for a user like me. Just knowing TW on the S4 is taking up 8gb just turns my stomach! Then there's my Nexus 4 experience (aka best Android experience available to date). There's a huge misconception in the Android community that you can just flash a ROM and get this silky smooth experience. Well you can't. So I'm going with the S4 optimized by Google. I would consider the One as well as long as its by Google.
After having the Nexus 4 for the last few days I can only say that the functional difference, the smoothness of the OS, compared to anything else, is abysmal. It's really top notch. And it doesn't have anything to do with processor speed or memory RAM. Its all in the OS itself. It's as good as, if not better, than the way iOS works.
At the time the Galaxy Nexus was available, the smoothness of stock Android wasn't so evident. Even with the updates from ICS to Jelly-Bean.