Theoretical limits are about 2GB and most of my testing has been in the 5mb to 500mb range.

You'll be much happier if you format the disk before using it over the serial link. Formatting works, it just takes a long time to touch every 512byte block over the serial link. Especially with larger sizes.

It defaults to 57.6kbps. On systems that have extensible control panels (System 6 & 7), the Control Panel can be used to select slower baud rates. On earlier systems, you don't get to change it, although 57.6kbps seems to work ok on the 512k.