I have well over 1000mi on my O-ring chain and it still hasn't required adjustment. My original chain cooked early and I had one of the first Symbas. The chains are sub-standard. Fortunately, the chains seem to be the exception rather than the rule.
On the size issue. Whenever I think about another bike I keep finding myself coming back to a small displacement bike. There are pluses to bigger, but as you mentioned the people you meet and just the difference in mindset when routing a trip continue to outweigh the hassle of going 50miles to get to the same place that 20miles on the interstate would take me in under 10minutes. There has nearly always been something I'm grateful having encountered in the over an hour spent traveling the "wasted" 50 miles. That said, would I go 100cc again? I suspect not, but I'm not sure I'd go much bigger either.
You are absolutely correct that the Symbas are what make this trip so very interesting a compelling. Of course, while the Symbas are the cake the riders are definitely the frosting.