I have such a bike. The downsides: * It's heavier than a derailleur/cassette * More drivetrain losses * It's expensive. Upsides: * Maintenance is replacin

I have such a bike. The downsides: * It's heavier than a derailleur/cassette * More drivetrain losses * It's expensive. Upsides: * Maintenance is replacing the oil about once a year. * You can shift from a stop. * Easier to adjust.