Metal vs Synthetic Devices for Extended Wear

I’m sporting a plastic cage and have been wearing one for just seven days, but it looks like I’ll be keeping this setup long-term, so I’m considering a device that lasts months or more. Most options are synthetic materials, yet the MM stainless model seems to be the favorite for extended wear; nothing beats steel when durability is key. A custom fit would also make a significant impact.

Am I right to consider steel if I plan on keeping my lock secured for several months?