I was able to test with both a 128k and a 512k and they weren't able to boot. After attempting to boot from the floppy, they came up with sadmac error code 0F0062, which doesn't seem to be documented in either the Apple KB or The Dead Mac Scrolls. When investigating, it looks like there's a sense code that determines the number of sides the drive supports? I'm not sure. Looking at the code, am I right in thinking the sense codes are handled by the CPLD?
If you've got time to look at such things, I can send you a 64K ROM 512K machine to test with.
I also hooked it up to a Classic, and it seemed like the Classic didn't recognize that the floppyemu was connected at all. It didn't try to boot from it, and didn't get a disk on the desktop. On the floppyemu LCD, it looked like it never received a seek or read, the tracks/sides never changed.
I hope to investigate some of this, I'm still familiarizing myself with the code.