The last piece of my card (the mPCIe bridge) arrived today. The AirPort came last week. The build went fairly easily, if a bit fiddly. The bridge is one of those without standoffs for the screws, but I found that a motherboard screw tightened from underneath the bridge secures it well, while holding against the mPCIe slot's spring to level it out.
Windows had no trouble installing it (something that worried me while waiting for the parts), and OS X was very happy with it. It worked okay as the sole connected adapter, but seemed a bit sluggish in Windows - my mail is stored on a NAS for use in Thunderbird on both platforms, and switching inboxes would lock up Thunderbird for a spell. My iTunes library loaded slower, too, but I suspect it's more throughput than anything else (270mbps vs 1000). I'm running both AirPort and onboard ethernet in OS X without issues right now, with the router less than 2 metres directly above the rig.