As a person that has been there, done that, & got the t-shirt so to speak on this subject matter w/ the S3, I would highly recommend waiting until the Note 2 is released on all of the major US carriers.
If there are no major differences than just leave it all as one, but if there are numerous / noticeable differences than separating them might be a good idea. I remember when the S3 was first released I was trying to help a member figure out where to turn her Wi-Fi on & off. I told her it's in the "Ongoing" section when you pull down your notification bar. When she said there was nothing in her "Ongoing" section I thought she had no idea what she was talking about as she was new to smartphones in general. Unfortunately, I couldn't help her out. As time went one it was later discovered that the Wi-Fi on / off is in a different section on some carriers. I have the Verizon S3 & found out that lady I was trying to help that day had a Sprint S3. While this may seem minor to some it can be quite confusing when the device is released & you are unaware of the differences between each carriers version.
There is no use deciding now on the "what if's". Once you have all the facts / differences in front of you then make the decision. When the S3 was first released I was "all in" so to speak on separate forums, but looking back on it now it just really wasn't needed. Hope this helps.