Yeah, I already tried this. From the documentation I could find it all works OK *if* your motherboard can physically handle the reading and writing of single density disks. Mine can't, and I don't think any driver can make that happen. I replaced the drivers as you described and got everything working, but when trying to read TI files off the drive it was corrupted, inserting fake/dummy files and being unable to read the ones that actually kept the correct name. Also, when I ran the 'test' utility it confirmed my motherboard does not work with single density.
If you or others think this is still something that can be worked around I'd love to hear details.
I'm basing my comments on the manual.txt file found with TI99-PC which explicitly states how certain motherboards are incompatible and includes the testing procedure I mentioned. Specifically:
The stock TI Disk Controller handles only Single Density. If you
have one of those Controllers on your TI, your PC must be able to
handle Single Density too for a successful floppy disk transfer
between TI and PC.
If your PC doesn't pass this test, then this software is not for
you.
I tried using the Omniflop drivers on a Windows 2000 PC and a Windows XP PC and neither one worked or passed the aforementioned test.