Alright, went ahead and bought the Steam version because holy shit, it exists.
One of bit of weirdness - before I could apply the R-18 patch from Otaku-Plan's website I had to go to Steam\steamapps\common\TAIMA MIKO\System and delete a small file named "window" The patch wouldn't work until I did that. The patch put the file back, so no idea what the fuck it even is.
I was curious how the official patch would handle Miko being Miko, and the answer was she talks somewhat like Kenshin when he's in Oro Oro mode. At least while she's calm. ("Proper" grammar goes right out the window if something is molesting her.) Which works, I think.