NetBSD 6.0 doesn't like how the keyboard resets:

[Linked Image from i.imgur.com]

Neither does NetBSD 7.0:

[Linked Image from i.imgur.com]

NetBSD 8.0 don't like it (rock the casbah, rock the casbah), but continues past that point until booting into the microroot:

[Linked Image from i.imgur.com]

At that point it refuses to recognize that there's a CD-ROM, possibly due to the obvious SCSI errors indicated in the previous screenshot:

[Linked Image from i.imgur.com]

So, if anyone was curious as to why the driver is still marked MACHINE_NOT_WORKING despite SunOS 4.1.4 more or less happily installing, there you go.