The answer is usually easy to determine based on your particular situation:

• Can you keep the appliance sheltered from weather conditions, in a cool and dry place under a roof or awning?
• Do you expect to carry the plancha from one place to another often?
• Will wind influence the flames and their correct development, requiring repositioning of the plancha every so often?
• Do you have enough space to store the plancha during the winter?
• A plancha fixed to a trolley can be handier if you intend to be moving the appliance around. Tabletop planchas are not suited to such manoeuvring, as you can hardly push a trolley while holding the gas bottle and ensure the plancha doesn't fall!