What main features should I look for on a petrol garden chipper or shredder?

•  Powerful petrol OHV engine from around 140cc upwards

•  A large cutting capacity around 40 – 60mm or more

•  Dual purpose mechanism – a robust flywheel with sharp, strong blades for chipping, with blades, flails, hammers or both for shredding *

•  Dual purpose hopper/chute for dealing with branches and loose material

•  Heavy duty construction

•  Transport wheels

* Or a similar strong and durable cutting system.