I just got an MS290 with the flip-caps and was concerned (because of posts like these) but after 20+ hours I have had zero issues with them. They require a bit more care when putting them back on. You can't just drop them in and spin them. You have to line it up, it only goes in one way. I appreciate the quarter turn and positive lock design.
This guy puts it best. Over engineered POS. YouTube - Flippy caps part two.