may not be original for the -8 but I just don't
want to deal with something
the size, weight and unreliability of a RK-05.
SIze and weight I can understand, but I've found the RK05 to be the most
reliable of the demountable hard disks, and pretty reliable by any
standards (I've had many more problems with floppies, for example).
The RK05 is also a fairly easy thing to repair, decent docs exist, and
_I_ have the alignment disks and spare herds (not a lot of help to you, I
guess).
Personally, the device I'd go for on a PDP8 (Omnibus) would be an RX01 or
RX02 on an RX8E controller. I am told those are hard to find, though (I
do have _one_, it's in use...)
-tony