We have a large number of NetWare 3.1x clients, and have been very happy with
it.  The clients that use it (and almost all of them used ARCServe prior to
ADSM) like it very much, despite the lack of the GUI - but they would like to
have one too.  We have not done much with tuning, other than to set the
Processorutilization parm at 10 in the DSM.OPT file.  I believe that
(almost?) all of our servers are 10Mb Ethernet, We benchmarked a restore rate
of 1GB/hour on our network with this configuration (That was 1GB of disk
space - we run with compression all of the time).

The pain in a NetWare client for me has always been the maintenance of
NetWare, and being sure you are at an acceptable level.  The comments posted
by ERL are right on - be sure you understand them before moving forward.
Other than that, we've been very happy.  Good Luck

Jerry Lawson
jlawson AT thehartford DOT com