To me, the biggest difference is that the powertrains are completely different. The 6 cylinder is incredibly smooth, power is huge and it gets exciting as it quickly revs to the 8800RPM redline. Although the K1600 Grand America is more expensive, high tech, etc., in many ways I actually prefer my Pure R18 at least for shorter rides of 150-200 miles. For distances beyond that, I prefer the Grand America. For me, one big drawback of the Grand America is that it is really top heavy and is a challenge in slow and tight maneuvering. Once it gets going it is quite agile and great to ride. I have to admit what I really love about the R18 (which I keep in the Rock Mode) is the genuinely visceral feeling I experience whenever I ride it. It kind of reminds me of the Bonnevilles (650 and 750) I started out way on back in the day. I got an incredible deal on my R18 and it puts a realky big smile on my face whenever I open it up. I find the handling to be great and after adjusting the rear suspension properly I have never dragged or scraped. People might think I'm crazy but in some ways I prefer my basic R18 to the much more expensive Grand America but that's what riding bikes is all about for me and everyone else...