To keep it short, yeah, rare.
FWIW It may be the slowest VAX ever created* (or, the 725?).
The essence of BA23 based system collecting nowadays
seems to be to have the logo'ed power switch and the
unique cards. The rest of the system (except the software)
is nonunique and interchangeable AFAIK.
*I have a vague recollection that the uVI chipset was created
by DEC proprietary in-house fabrication(?) techniques...
Upon seeing the results they then consulted with outside
chip fabricators for the uVII.
John A.