I use dd to test iscsi performance on the guest VM, not sure how accurate this would be, but I thought I would share.
PVE Host:
PVE 1.7 on Dell PE 1950
1 Dedicate 1Gbit nic
Jumbo Frames @9000
iscsi with LVM
SAN:
OpenIndana(Solaris) on Dell PE 2950
1 Dedicate 1Gbit nic
Jumbo Frames @9000
ZFS...