I can't answer the PC question, but I can help a bit with the modern Mac question. I use zip disks a lot, but mainly for transport to the modern Mac, not from it. A Sierra Mac can read HFS zip disks (which is the only thing System 7 understands), but cannot write to them. If you have an OS 9 bridge machine, that is more useful since it can both read and write HFS+ (as can the OS X machine). Also, an OS 9 machine with USB ports can handle HFS+ USB flash drives. So handy!
Have you tried installing System 7.5 on the Q700? I don't know if it would help, but I know there was a point at which the Mac became capable of reading PC-formatted zip disks. I used to rely very heavily on zip disks in the mid 90s and it amuses me to no end that I can now use them to move files between different vintage macs.