However, I put 500-600 miles a week on my bike commuting and I do the actual work on the bike, so here's the perspective from someone who is concerned with these things.
In general, there are 3 maintenance "issues" that matter, the chain, the carburetors, and the valves. Most of the other maintenance items (spark plugs, oil changes, etc.) Aren't that tough to do and they typically are spaced out enough that you won't notice unless you ride a lot.
Of the 3, chains are the easiest to deal with. Should just lube them every couple hundred miles. Just takes a little spray. Nothing to it really. It takes me 5 minutes once a week, although real maintenance nuts will claim you shouldn't wait that long. I wouldn't let a chain drive influence your decision.
Likewise carburetors. Fuel injection doesn't need adjusting where carbs need a choke and sometimes some twists of the adjustment screws. My bike has 4 carbs and every now and again they need to be dialed in to work right with each other. And my bike has a fairing and other problems in getting at the carbs to do the adjusting. The C50 has fuel injection and the America has carbs. But the America only has 2 carbs. And they are out there in the open. Yeah, slight disadvantage, but not much.
Valve adjustment is the biggest headache. You actually have to get in the top of the engine. And there's a gasket that can break when you do it. On my bike, getting at the carbs is duck soup compared to the valves. And I've got a 4 cylinder with 4 valves per cylinder (16 valves to adjust). And to top it off, my bike requires an adjustment every 6000 miles (every 3 months for me).
Sheesh.
But I don't think that will matter to you. Both bikes are 2 cylinders, maybe 2 valves/cylinder? Everything's real accessible on both bikes. And the adjustment interval for the America is 12,000 miles (don't know about the C50). I'm betting that's every year or 3 for you.
Both bikes are fine machines and I wouldn't let maintenance sway you much.
Of course, I'm a Brit bike fan. I ride a Triumph Trophy 1200. Mostly because it fits me and they're just generally stylish, unique, and cool.
So get the America.
