I have tried about everything for my ZIP drives.
The only thing that works ans stays working is IDE fix.
Especially when you are not using the internal IDE port.
This is by my knowledge the only way to get it runnung and keep it running after a diskswap.
And no it is not fast.Around 600KB/s on 68060.
With an other way of driving you can archieve about 1.5 MB/s but after a diskswap your zip drive is gone.