A 22' in Inca Gold, a 32" Silver sports Trunk (same material and construction) and recently a sale item 29" in Navy. No problems to report.
Our experience over the flying years is that thieves will take anything and everything they have the opportunity to get their nimble hands on. It isn't the colour, shape or materials but the chance to take it quickly, and get away with it. Grubby, cruddy, or shimmering, they take it all if given the chance.
Leave luggage unguarded for a quick second at the train station, use the Lavatory for a minute while the airport carousel warms up, or walk away from the luggage rack on the train and it and your well packaged contents inside vanishes immediately.
I have even watched passengers leave their luggage alone to queue in line at the nearest American Consulate ( Starbucks ).