According to http://www.applefool.com/se30/, System 7.1 should be able to connect to OS X 10.12 Jaguar as long as AppleShare WS 3.5 is installed, and possibly MacTCP 2.0.6 and Network Software Install 1.5.1. I've tried with and without the TCP and networking software, but no dice. The 10.2...
I was curious if SCSI2SD would work with a Toshiba Flash Air Wi-Fi SD card - that way I wouldn't have to shutdown the Mac, remove the SD card, and insert in to another Mac to transfer files. Anyone try it? If not, I might give it a shot. I just don't know how SCSI2SD would react to files...