However, being a Mac user it seems my options are much more limited.
Common misunderstanding. I'm a Mac user and just about every mechanical keyboard made works as good on a Mac as a PC. (Except an old Choc Mini and some tenkeypads... but literally no even semi-mainstream ones.)
Mac Layout (not just the command key, would also like brightness keys, media keys, launch pad, mission control, etc.) - I know I can assign keys for these functions, but if they come pre-labeled that's a plus.
I doubt you'll find any sets that are labeled just like a Mac, but you can map them all easily. If you wanted to, you could get some custom lasered keys from wasdkeyboards.com for this purpose. Personally, I just mapped the things I use from the top row to some of my F keys and never looked back. I use the Print/ScrollLock/Pause keys as Mute/VolDown/VolUp. I love that... even better than a Mac keyboard.
This works great.
Sound - Not too loud, but does not have to be silent either.
Pretty much all mechanical keyboards will be louder than say an Apple Bluetooth keyboard. But some are louder than others. For the most common switches (Cherry MX) the sound primarily comes from two things: 1) The key bottoming out when it stops, and 2) A purposeful click from the switch.
#1 can be solved by typing lightly, or by using sound dampening pads or rubber o-rings around the stem of the keycap. But really, this is only necessary if you are in a really sound sensitive environment or you clank your keys hard. (With my typing style, it's not all that much louder than some rubber dome or scissor switch keyboard.)
#2 is only an issue if you want it to be. The most common clicky switch is probably the Cherry MX blue switch. (And also the green switch, though less common.) Black/red/brown don't make any clicks. There are Alps style switches like on Matais too, but they aren't as popular around here. (Not to say there aren't fans or they aren't good.)
Optional/Would Like:
Backlit
Bluetooth/Wireless
You probably don't want both of these... backlit uses quite a bit of power, and bluetooth needs to be a battery keyboard. I don't think such things exist because of this. As far as bluetooth, the only ones I'm aware of are all full size and the Matias ones. There may be some more obscure ones, but not sure.
I came to mechanical keyboards like you seem to be once. Quickly I realized that it's better to find a good solid and well-made board first, and then adapt to it.
Not to push you away from what you want, but I think something like a Coolermaster QuickFire Rapid with perhaps Red or Brown switches would be a good board to start with.
Of course, the Matias Laptop Pro is the closest thing to what you describe... but you already know about it. I think if we took a vote most people would recommend something other than an Alps switch though... but to each his own. (I've owned quite a few Matias boards.)
