Disk Keeper instability?

[fredJ]

I have tried to write a couple of disks. They work on my Twin Famicom well calibrated, but sometimes the writings give Err 27 on a FDS I also own.
My friend tried them with his FDS and he got Err 27 with most.
Do you know if the Disk Kepper is unstable and you can't rely on it? Or is it fdsloadr maybe?

[fredJ]

My twin is well calibrated. I recalibrated it to work with all disks.
My FDS is less well calibrated on purpose, to try out rewritten disks.

I don't know the answer to your question and don't feel like guessing. I assume you think you know. But it does seem like Twins are easier to calibrate for some reason.
Anyways, I was asking a question in my thread, that is my concern.