Chain vs chainless options Could someone provide a comparison between having a bike with a chain, with a shaft drive and with a belt drive like the Gates Carbon Drive?

It could be good to know who fares better in terms of low maintenance, durability, and efficiency.
For fixed, single speed and hub gears belt drives are great, if slightly more expensive initially.  They don't work with derailleurs.

The key difference is that as chains wear they also wear the sprockets and chainrings and therefore all need replacing if you leave it too long or don't lubricate often enough.

Belt drives are used in many applications which are harsher and less maintainable than bike drivetrains - 70k Miles @ 3000 RPM for a car cambelt should give you confidence to fit and forget a belt on a bike. Also used on big motorbikes (Harley, Yamaha, Buell) as a chain replacement.

Shaft drive is too inefficient and heavy for practical use on a bike.

I have both chain and belt drives on different bikes - they do different things but are both fit for their respective purposes. The chain needs lubricating frequently and replacing from time to time. And the belt-drive simply doesn't.