Apologies in advance for the potato pics.
I'd been without a mechanical for a while. I've had them in the past, most notably a Focus FK-2001 with complicated Alps, along with a couple others I got used (but no Model M's, unfortunately). Finally decided to fix that earlier this week, and ordered one from Mechanical Keyboards. I asked for a drawing, and my box arrived adorned with this:

Well, the drawing gave the brand away, but which one?

The best one, of course. I ordered as soon as I saw they were in stock, somewhere around 3am on Thursday, and it took about 2.5 days total to arrive, so pretty quick. Of course FedEx didn't even bother to knock on my door.

The caps are nice and thick, and make a pleasantly solid thock when bottoming out.

As far as I can tell by looking at the windows on the Scroll Lock and Num Lock keys, the tops may be slightly thinner, but are still plenty thick. That said, the PBT seems somewhat translucent, as the LEDs in the WASD cluster can easily shine through the caps, illuminating the legends reasonably well. These keycaps should work quite well with a Shine (there's enough bleed through in the legend area), but probably not as well with most other backlit keyboards that put the LED at the bottom of the switch. The potato is exaggerating the contrast here, it isn't quite this contrasty in real life.

The only negative I've experienced so far is the windowed keys. The hole for the window is drilled into the keycap as opposed to molded in, and there are some small plastic burrs around the window. My Caps Lock key turned out pretty well with no real burrs, but on the Scroll Lock and Num Lock keys you can definitely feel them. It's not a big deal for me, and I'm sure they'll wear off with time, or I could carefully deburr them, but I figure it's better for people to know than be surprised.