The 27 series offers a good stove for the lone walker or two people. The pans are smaller, along with the compact stove that takes up minimal room in the rucsack, you can also use bigger pans on the raised supports on the upper windshield, when required.
The 27.6 is made from aluminium, this is a durable lightweight material that conducts heat uniformly and quickly, the aluminium pans are coated in a non-stick coating that makes them easier to cook with and clean, but are more susceptible to scratches and abrasion.