I don't think I've done an update in this thread since the one above. Long story short: the migration went quite well, I've got the mini up and running, I've been able to hook up my external HDDs, there was no problem with the VGA to USB-C adaptor, and this little space gray i5 totally rocks.
Bootup is scary fast, and I've even been able to get my Adobe CS5.5 apps to work with Mojave. The fan is silent, and if there is coil whine, I'm not recognizing it as anything out of the ordinary. Yeah, I've had issues with Bluetooth, specifically with a Bluetooth mouse, but I had a wired mouse available and that's been serviceable.
So, all in all, I am happy. I do feel bad for those others who've encountered all sorts of problems. I must be one of the lucky ones.