Indeed, just like that but without the fatigues or the wicked mustache.
I currently have the case apart but the Mini is running. I'm taking some wordier notes, but i'll give the tl;dr version here. I used V8 of Ross's installer, which worked without any problems at all. The MicroSD card is a 64GB Sandisk Ultra Plus UHS-I and the SD to IDE adapter, linked previously in this thread, appears to be a Sintechi adapter though I forget if it is unlabeled/generic or not. Installing the new "drive" was easier than removing the old one and was painless. OS 9 initialized the disk without complaints, I copied over the goodies from the Extras folder of the disc, set it to restart from the hard drive, rebooted, did the first boot thing, restarted again, and timed the boot from when I heard the chime to when the desktop was loaded as taking 40 seconds. I didn't do any timing or benchmarking of the 40GB hard drive, though I may put it back in to do so while i've got the case apart. I have yet to benchmark the SD card, but my initial impressions are good.
About possibly mounting an SD extension cable/ribbon to the rear of the case: I could either clip off or bend back the metal piece of the kensington lock that is part of the top shielding, and I would also have to cut a bit into the black fan shroud plastic that directs airflow out the rear of the case, but it is far enough away from the majority of the airflow(as well as the fan) that I think it could be done without impacting thermal regulation in any significant way. I will obviously also have to cut/file away some of the white plastic housing around the lock port to make room for the secondary SD card slot, but in my head at least, it all seems feasible.
After I do some initial baseline CPU benchmarks, I may conjure up the courage to remove the logic board and desolder the 4 jumpers/resistors to see how stable the Mini is at 1.5GHZ. But, one thing at a time.
*edit: I find myself encountering the frozen mouse cursor bug, so that sucks. I guess i'll need to hotkey the shut down tool; too bad I didn't already do that.
*edit 2: I attached a photo of my MacBench results for CPU/Disk. I didn't take a comparison test with the old hard drive, so I don't know whether this is a good, bad, or neutral result. I haven't overclocked yet either, so this is the stock 1.25GHZ.
*edit 3: Attached is the MacBench results with stock CPU and the original 40GB IDE hard drive. Unless this is one of those tests where the smaller number is better/faster, these results seem to indicate the SD card setup is faster than the stock drive. I just did the basic main test without changing anything, so maybe it's somehow a fluke?
Stock HDD: 1787
SD Card w Adapter: 4868