I have used the driver, I get only slightly better speed (something like 0.2 MB/s). I could get exact numbers if you want me to test again.
I tried shadowing and it made no noticeable difference oddly.
With a QD6580 and XTIDEUB I get about 4MB/s and the 6500 I get around 3.1 MB/s on my 486. Actually a little disappointed. Using an Appian ADI/2 VLB card and the latest Adaptec driver I could find using the same drive I get 5.8MB/s
I'm setting up a system with one of the cheapo 386 baby AT boards that have the 40mhz AMD 386DX (board model MA013). The system would not boot from the floppy drive. The drive lights up, spins, head moves but no dice. I have checked the BIOS settings for ISA bus clock, floppy drive setting, etc...