An HP LaserJet 5100 was having intermittent network issues: it was lose connectivity to the network and error out in the middle of a print job. Finally, the OEM JetDirect 610n card gave out. Searching the internet for an exact replacement, I came across many bad reviews for this particular card. One even had a link to HP's support website advising technicians and consumers about premature failure with the JD 610n and using a JD 620n as its successor.
Hearing it straight from the horse's mouth (HP), I followed their advice and opted for the JD 620n instead. For a mere $10 more than the JD 610n, I bought the peace of mind knowing that I would not have this problem again for a long while. Plus, even HP was steering its field technicians towards it when they encountered problems with the JD 610n. The delivery was right on schedule and the card was very easy to install. We had the printer working again without any more network connectivity issues in less than 10 minutes. This was a very wise investment.