Yeah, the solo chin strap on the kevlar was uncomfortable (never did get that whole button snapping thing down) and it easily came loose, especially while IMTing. The MICH has better padding and the airborne retention straps built in. It’s also a tad lighter and made to hold NODs more securely. Also, instead of the unsnappable button on the chinstrap, it’s a plastic clip that doesn’t come undone and is easy to work with.
...and I’m guessing the NCOs still refer to them affectionately as “brain buckets” :-)