Not having seen the Rock 'N Roll Hamilton, I just looked it up and I must say, it's very funky - but in a good way! I'd say go for the Rock 'N Roll one strictly because everyone has the North/South version. I like to be different with my bags so I'd personally go for the one that's unique.
You also have to think of it this way: because the Rock 'N Roll has a punked up flair to it, it doesn't look like it could be dressed up the way the North/South one can. Are you looking to dress it up or are you looking for a more casual bag?
I love both designs of course, but between the two, I'd go for the Rock 'N Roll version, but it's up to you!