I opted for the 4021s because of the deal I got, but haven't regretted doing so, even when stealthing (like last night!). Scott may be right about the cable pressure, since at some point, it'd have to rotate to go out the back of the hat, but that likely wouldn't be a problem if you don't do it every day. I also like that the 4021s have a slightly smaller profile because of this.
I could see the 4023s being uncomfy, though! ... but you weren't asking about those.