I have an ACA500 with an HXC Rev B/C floppy emulator. With everything connected, I cannot write to any floppy--it simply errors out with a number of write errors. I cannot even create an ACA500 emergency flash disk. Remove the ACA500 and everything is happy. I've update the HXC to the latest firmware flash, but have yet to do anything with the ACA500 since I cannot make an emergency disk for it first.
Just thought it was an interesting 'problem'. Reading from the HXC works flawlessly.