Actually, gvpscsi.device v4.x forms the basis for GuruROM, with the latter supporting SCSI Sync on the 33C93A. v3.x is the same as v4.x (for the A500/A2000 Zorro boards), but the earlier version level supports the buffered DMA Series I boards. The 4.x series removed the old card support to make room for the newer CPU+SCSI+RAM products. GuruROM makes use of the adapter as the driver code to support both controllers and Sync exceeds 16K, which is the available space provided for ROM on the A2091 and GVP Series II boards.
If Unexpected Status errors are coming up, SCSI termination is probably at fault (or a bad cable), and GuruROM will encounter the same thing, if not be worse due to speed.