Originally posted by fikkser lol.
I think the plastic will be very strong. I bet it will be made of high quality durable plastic. Plastic is good against bumps too. I don't think the mount will break before the elements or anything else in a bump or what ever.
I am rough, and clumsy, and I torture my kit. So, the plastic mount is a factor for me and others. Plus you attach and reattach a plastic mount lens a thousand times. There is no data or evidence for this in terms of durability. Plastic will start to shave off eventually and it could end up in the camera.
Metal mounts have been around a long time. They were engineered that way for a reason.
For me $200. is a LOT of money. I am not a rich. I can buy several used metal manual lenses for that instead, and I will.