As I understand it Pros -
They can last for thousands of hours.
They can be sized to transmit very large horsepower.
They can be very short making a very compact setup.
Cons
Pull on the bearings is quite a bit higher than v-belts
They do not have the give that v-belts have so they transmit 'shock loads' and 'transient torques' or something like that, which is rougher on everything. The sutorbuilt dealer I talked with said they should not be used with blowers.