The case creak is indicative of the quality of the clamshell cover material which, according to Neil Muyskens, was changed in 1999, and I doubt they've reverted back to IBM and Lexmark's previous recipe...
As I mentioned, in the boards where it occurs, it doesn't happen when you're using it. As far as I know you must actually pick it up and
flex it. It's beyond me why anyone even thought of doing that in the first place, or why it was supposed to be important. It's like complaining that your toaster doesn't bounce.
The caps also feel a bit thinner and do have more flex as well.
I've typed on half a dozen Unicomps from different periods—including one a friend ordered new a couple of months ago, one I ordered new about a year and a half ago (and returned because I didn't like the printing, described above), my 2009 BOS 122, and my 2006 GE/Marquette medical 101. And I've never experienced anything like what you've described.
These are PBT keys, not ABS like cheaper boards, right? What can possibly "flex" in an assembled IBM-style two-piece key?
And you say the caps feel "thinner"? When you're typing on them? How can you possibly determine the thickness of a cap firmly clipped to a stem? Or do you mean when you removed and examined them? You don't normally interrupt your typing to do that though, do you? That'd seem compulsive. I'm not a therapist of any kind, but it seems to me it'd be healthier to try to leave the caps on and not think about them so much. :?)
Okay, I was too curious: I just called my friend in Vancouver, and he's removed and examined two-piece keys from his 2015 Ultra Classic and a 1989 Model M 122-key terminal board, compared them, and proclaimed them identical. And I believe him, as he's one of the most detail-oriented people I know (even more than some of you guys!). He couldn't imagine how they could be made to "flex", either. He offered to try squeezing one with pliers, but I said I was pretty sure that'd be beyond the scope of our discussion.
Sure, if all you care about is the typing experience, it probably doesn't matter, but if you're interested in the highest quality Model M ever made...
Dude, sorry, I'm not chuckling
at you; I'm just enjoying the esoteric nature of the statement. ("esoteric: confined to and understandable to only an enlightened inner circle")
I'm glad we can agree they work equally well as, you know,
keyboards —that being, after all, technically, what they are.
And while I see Unicomps and classic IBM M's as equally durable, even if Unicomps
were slightly less robust, I don't know of any reason to think a Unicomp made in the last 9 years would prove less durable than an IBM from the '80s/'90s—which, assuming you're not paying $300 for a NIB one, is likely to have 10–20 years more use on it (probably full-time use, too, as BS boards were primarily for business back then).
So what aspect of "quality" remains? Sheer size and bulk? Well, I can't deny my grandfather's Lincoln Continental was "more car" than my Toyota compact. But stuff doesn't have to be as big and/or heavy to be just as good.
If you ask me, I think IBM and Lexmark lightened their plates over the years not because they were trying to skimp, but because they realized heavier plates were overkill and they were just wasting metal and paying unnecessary shipping. I think they realized people were
typing on these things, not hurling them at track meets or using them to stop artillery shells.
And while you and I think classic Model M's are beautiful, let's face it: To most people, they look like something from a thrift store. Non-geeks who want buckling-spring boards probably appreciate the option of buying more modern-looking ones that aren't of such epic (and necessarily
beige) proportions.
In other words, I think everyone's a winner. For the clack-loving, there are great options all around. IMHO, just the fact that Unicomp exists and is still pumping out Model M's, in this world so focused on cheapness and mediocrity, is a bit of a miracle.