Three recent acquisitions include a (NIB) Chicony 5181 (Monterey Blues), Apple Extended Keyboard II and an Apple Extended Keyboard.
Here's a short summary of first impressions:
1) Chicony 5181: First impressions are that the board itself feels a bit flimsy and cheap. I'm also not crazy about the recessed function keys, nor the small backspace and huge enter key. I do wish these switches were in a higher quality frame though. The switches definitely feel extremely similar to Cherry Blues, although I think it's a bit quieter, which I think I prefer. I also think the switches require a tad more force to actuate, which I also prefer. Overall, the feel is pretty good. It's an enjoyable typing experience, but would be even better with a standard backspace and enter key, as well as a higher quality case.
2) Apple Extended Keyboard II(M3501 -- 0312): First impressions are that the feel of the keys in this board have just a tad too much stick (could be smoother) to each keypress. The tactility is nice, however when typing at full speed the keys feel a bit too gravelly, which to me, interrupts the flow. It almost feels as though the sides of the keys are rubbing against something on the upstroke and they're about to get stuck or hung up. That said, overall, the feel of the keys definitely has its own charm but the aforementioned is simply too obstructive (for me) to make this a common driver in my lineup. As for the build quality, it seems solidly constructed.
3) Apple Extended Keyboard(M0115): The feel of these switches (orange ALPS) seem very comparable to Cherry Browns, although the tactile bump of the ALPS switch in the AEK seems to be positioned right at the top of the keypress whereas the Browns feel a bit closer to center or, to be more precise, a quarter of the way down. The gravelly sensation of the AEK II is nonexistent to my sensibilities here. There's no interruption in flow when typing at full speed, and I find myself preferring the feel of this switch over the Cherry Browns in my Filco MJ2. Although not clicky, I do tend to find the clacking that this board produces when bottoming out to be unobtrusive and even enjoyable. As for build quality, this one also seems to be solidly constructed.
Out of the three, the winner is the Apple Extended, at least based on initial impressions. I'd go so far as to rank this one as one of my favorite boards right alongside the Model M, but I'll put it through a few more weeks of typing hell before drawing any hard conclusions.
