I can say for sure that the e6410 pxe boots just fine using the trunk (dev) build of 1.2.0.
The e6410 is a bios only system that does boot with the undionly.kpxe. Since you said that you had an older version of FOG installed, can you tell me what you have defined for dhcp option 67?
When iPXE boots, there is a series if hex values that indicate the build beyond the version number. What is the build number.