After upgrading an OES2 SP3 cluster from SLES 10 SP3 to SLES 10 SP4 (which is supported by Novell since September 9th, 2011), we had a lot of problems with older HP JetDirect based printers (2420,2430,5200) and with older HP printers (1320) attached to Digitus DN13007 print servers. They just stopped printing altogether.
I reinstalled both cluster nodes with SLES 10 SP3 and POOF problems disappeared.

So do not upgrade to SLES 10 SP4 when using older HP JetDirect based printers and/or exotic print servers.

Another thing is RAW vs. LPR/LPD.
With native Netware 6.5 SP8 all but one printer in our environment (around 100 network printers, both HP JetDirect and Digitus DN13007 print servers) worked fine using RAW (Port 9100) printing.
Ever since we USE OES2 SP3/SLES 10 SP3 we had to change many printers to LPR/LPD to avoid problems (Postscript errors) in Office 2003 applications.

Generally speaking, the product iPrint has become a lot worse lately.