I understand what he was getting at and we're attempting to incorporate something similar for the Canyon Cages with the addition of that delrin stopper. I just don't see it being financially viable for the small rears as a custom piece like that would cost us quite a bit to have molded and made and would probably run $85-$125 to the end customer. If the plastic piece is nearly $100 to replace anyway, why not just replace the entire small rear bar for the $87.50 we currently charge?
Any idea how much TopBlock charges to replace just the plastic piece? If the set is nearly $700 you can bet it's a pretty penny to replace just the plastic piece. Keep in mind, although it looks like it, this stuff is not just your generic cheap plastic. It's, more than likely, some type of polyethylene or polyoxyethylene which can be very pricey.
It's a great idea in theory and I could see how it works for TopBlock (because that piece is the bulk of their bar) but for our application, I just don't think it's necessary.