To test the silicone barriers, iFixit exposed the 2018 MacBook Pro keyboard to a fine, powdered paint additive and the team observed that the dust remained at the edges of the membrane and away from the switch. However, adding more particulate and throwing in some "aggressive typing" caused the dust to penetrate beneath the clips and get to the switch. Taking it a step further, iFixit added some sand to the keyboards and found that doing so caused keys to stop working. So it looks like the the barriers do a decent job protecting against dust, at least in the short term, but larger particles may still be an issue.

Apple has faced lawsuits over its butterfly switch keyboards and last month, it finally acknowledged the issue by launching a repair program for certain MacBook and MacBook Pro models. It's good to see that the company is making some effort to fix the issue in newer models, but as iFixit notes, only time will tell how long these silicone membranes hold up.