Is anyone else seeing terrible network writing performance using VMDP 2.3 on Windows?

Test Enviroment;

1 SLES 11 SP4 Xen host, fully patched
1 OES 11 fully patched with NSS share
2 basic Windows 7 SP1 Xen virtual machines;
- both with latest Novell Client,
- both are the exact same patch level
- Both have a single dedicated bridge/NIC on the SLES 11 Xen host connected to same switch
- Only difference: one has VMDP 2.2 (rtl8139 nic) and one has VMDP 2.3 (netfront nic). Both VMDP 2.2/2.3 were installed in accordance with the documentation and readme files (twice, just to be certain).

Test results;

- Writes to the OES server share with the VMDP 2.2 machine are averaging 700Mbps. Reads average 700Mbps.
- Writes to the OES server share with the VMDP 2.3 machine are averaging 450Mbps. Reads average 700Mbps.

Our production environment has almost a 50/50 mix of read/writes - our users will feel this and it will hurt productivity. We can not deploy this as is. I see from the bug fix list that there were several xen improvements, but nothing to indicate there was a performance hit. When we uninstalled 2.3 and reinstalled 2.2 - performance was restored. We are not so desperate for the fixes in 2.3 that we can't wait for 2.4, but we are curious if others are seeing similar behavior in similar environments using VMDP 2.3, or perhaps there's something we are doing wrong?