Sorry for the delay, I did a rebuild of my test system these days.
I reproduced what you have and was able to successfully increase the VMFS volume as documented in the link I provided (except VMFS was partition 3)
What I did was to install ESXi 4.1 U2 on a 900GB disk, then upgrade to ESXi 5.0 and increase the disk size to 1.9TB. Then I opened an SSH session, used fdisk to resize/grow the VMFS partition (which btw. is a primary partition with the additional new disk space adjacent to it) and expanded the grown partition using vmkfstools.
If you did not already rebuild the host, please post the output af fdisk -lu as well as ls /vmfs/devices/disks
André