[Scott]

True, Sauron could've used Sam's ill feelings towards Gollum against him, but if Sam was the ring-bearer the whole journey, as Frodo was, might the same wisdom Gandalf gave to Frodo be imparted upon Sam as well?
Yes, throghout the journey, we see why Tolkien set up each character as he did with each one having their own foibles. However, if you look at the begining of the story, many of the same feelings were felt by Sam and Frodo alike. For instance, the scene in Moria concerning Gollum as was afore mentioned is one place where the reader can see that Frodo disliked Gollum very much at first, much like Sam does.
I think that to determine whether Sam could be a possible ring bearer you should not look at where Sam was at the end of the journey, but instead where he was at the beginning. Then from the beginning, you look at how the journey would have changed Sam to see where he would have been at the end. It's not about the destination, but the journey itself. I think that he would have been in such a position very similar to Frodo.