> My present XZ3 is just too good (despite the minor issues) to do a reset

not that I want you to prevent flashing other Tama - this is a correct way of spreading the port - but we have now ability to make filesystem backup using sdcard. That way I am able to flash/restore development device quite fast to test OTA, for example. That works via telnet and usb connection to the phone, so not trivial. But nice to have such backups