You might remember that I told you about this problem already in my very first reply:
https://forum.amiga.org/index.php?topic=75365.msg853537#msg853537In the meantime I change one of my programs to support BufMemType. It's attached to this post. Copy that lha file to your Amiga and unpack it somewhere where it can be found by the CLI, for example to the C directory of your boot partition. (remove the .zip extension, it was only added because the forum software does not allow .lha files)
It's a command line program. It takes the partition to act on and the parameters which shall be changed as argutments. If no parameters are given it just outputs the current values.
So open an Shell window and enter
changebootpri fs3:
Check the values for Mask and BufMemType.
Now enter
changebootpri fs3: mask ffffff bufmemtype 200
Repeat that step for all partitions on the HC+8.
Now reboot. It's probably a bit slower than before, because it has to copy buffers forth and back. But it should no longer throw DMA errors.