I am of the opposite camp... If you are ruff on sunglasses... GO GLASS
. One or 2 fine scratches on plastic lenses and I am sure to get head aches so out the window they go. Never fragged a glass lens though. Costa has excellent service if you treat the folks on the phone with dignity.
My father had a pair sent in but they were no longer able to fix that model... They invited him to pick a new model and sold them to him for below dealer cost as a good will gesture,
Glass lenses and all the tinting and coating being sandwiched between 2 thin glass layers is the main reasons I choose Costa... But I assure you... They sink like a rock so looking over the side of the boat 50 miles off shore without a "croakie" is very bad with your brand dang spankin' new Costas first day out