SunOS vs. Ultrix comparison

[K P Donnelly]

We are currently thinking about buying a Unix fileserver which will also
be required to run our program libraries from terminal sessions. 
Obvious candidates are something like a DEC system 5100 or a similar Sun
machine.  Among many other factors affecting the decision is the
relative merit of the SunOS and Ultrix versions of Unix.  Can anyone
tell me anything about this?  I am not familiar with either of them.

e.g. I have heard that SunOS has "shareable libraries".  I am not sure
what these are, but they sound very like the dynamic linking of object
files at load time which Edinburgh University's EMAS operating system
(now disappearing) has had for over ten years, and the lack of which I
find intensely frustrating as I try to move our program libraries to
Unix.  Makefiles are a very poor substitute.  Can anyone tell me whether
SunOS shareable libraries are really that good, or whether Ultrix is
likely to aquire anything similar.

Another thing which I find frustrating as we try to move to Unix is the
way that many utilities strip the eighth bit at every opportunity.  Does
Ultrix have better 8-bit character set support, perhaps carried over
from the DEC multinational character set on VMS?

   Kevin Donnelly