Well let's hope they make a better one than BMW is lately. Taking a look at
this thread shows a survey of 350 bikes where this a 1 in 8 chance of your shaft drive failure in the first 50,000 miles. And that's not a cheap item to replace.
Now you might say; that's BMW, this is a Triumph. Well then we'll go to the Rocket III. Triumph has already been subjected to
this recall on Rocket IIIs for leaking final drives.
But it's not just trust in your final drive that leads me away from shaft driven bikes. Repairs are definitely more expensive than chain or belt. There's also ease of changing the final drive ratio with a chain and sprocket setup. How many of us in here have changed their front sprockets out to a different size to suit their riding style? Well you can forget about doing that with a shaft drive. Whatever they put in there, is what you're stuck with.
Now most people hate messing with chain maintenance. I personally don't mind, and it takes me all of 5-10 minutes to do it. My only wish is if they could come up with a chain and sprocket set that could last 50,000 miles. Otherwise, a chain is just fine for me.