(I almost said "robust" instead of "reliable").
We have an office that prints about 30,000 pages per month, mostly duplex,
from our HP3000 to a JetDirect-connected HP 8000N.  They print on
pre-punched 3-hole paper.  The problem is that the printer jams all the
time. We have had the printer for about 18 months & have had various parts
replaced, and it still  jams.  Can anyone recommend a printer that has
worked well for them printing mostly duplex output?

By the way, the reason that they are doing duplex printing is to reduce the
space it takes to file the output (payroll records).