Many thanks to all for your help.
But now I think it was all termination issues or some other sort of SCSI-voodoo... I have checked again the disks on my recently acquired LC 475 (by the way, what a nice, snappy, tiny, versatile, underrated machine it is!) with the very same patched Drive Setup, and they check just fine! Ditto on the SE/30 (took about 3 hours!)
On the other hand, I tested the known-good Conner in daily use on the 7600/G3... and each time different errors show up :-/ I initally chose this machine because of obvious performance reasons, but in its current state it may not be the ideal setup for full function:

7600 mobo + PSU + 604/120 MHz card (now backup) + fully populated VRAM + 64M RAM = 3 EUR. The G3 @ 450 was a whopping $20. It feels so fast...
But now I think it was all termination issues or some other sort of SCSI-voodoo... I have checked again the disks on my recently acquired LC 475 (by the way, what a nice, snappy, tiny, versatile, underrated machine it is!) with the very same patched Drive Setup, and they check just fine! Ditto on the SE/30 (took about 3 hours!)
On the other hand, I tested the known-good Conner in daily use on the 7600/G3... and each time different errors show up :-/ I initally chose this machine because of obvious performance reasons, but in its current state it may not be the ideal setup for full function:

7600 mobo + PSU + 604/120 MHz card (now backup) + fully populated VRAM + 64M RAM = 3 EUR. The G3 @ 450 was a whopping $20. It feels so fast...