I just got this GVP Impact series 2 HD8+. The A500 recognizes the 8mb of memory, but when it tries to access the HD the message "unexpected status, $06 $07" pops up.
Booting from the floppy (os 1.3) I was able to access the HD. I had to click "cancel" a few times due to the error poping up.
I tried another HD, but got the same message and was not able to access this HD.
Well, it does add the 8mb of ram to the system fine.
My GVP Impact series 2 HD8+ is toast, isn't it? :-x