Re: Can't migrate VM between ESXi 5.5 versions: The product version of the destination host does not support one or more CPU features

What hardware version are your VMs?  I do recall that there were some bugs with the old-style EVC masks.  You may find that your masks work for hardware version 8 and older VMs.

The new-style Westmere EVC masks (for hardware version 9 and newer) are:

evc.featMask.cpuid.Intel = "Val:1"

evc.featMask.cpuid.FAMILY = "Val:6"

evc.featMask.cpuid.MODEL = "Val:0x25"

evc.featMask.cpuid.STEPPING = "Val:1"

evc.featMask.cpuid.NUMLEVELS = "Val:0xb"

evc.featMask.cpuid.NUM_EXT_LEVELS = "Val:0x80000008"

evc.featMask.cpuid.CMPXCHG16B = "Val:1"

evc.featMask.cpuid.DS = "Val:1"

evc.featMask.cpuid.LAHF64 = "Val:1"

evc.featMask.cpuid.LM = "Val:1"

evc.featMask.cpuid.MWAIT = "Val:1"

evc.featMask.cpuid.NX = "Val:1"

evc.featMask.cpuid.SS = "Val:1"

evc.featMask.cpuid.SSE3 = "Val:1"

evc.featMask.cpuid.SSSE3 = "Val:1"

evc.featMask.cpuid.SSE41 = "Val:1"

evc.featMask.cpuid.POPCNT = "Val:1"

evc.featMask.cpuid.RDTSCP = "Val:1"

evc.featMask.cpuid.SSE42 = "Val:1"

evc.featMask.cpuid.VMX = "Val:1"

evc.featMask.hv.capable = "Val:1"

evc.featMask.cpuid.AES = "Val:1"

evc.featMask.cpuid.PCLMULQDQ = "Val:1"

evc.featMask.vt.realmode = "Val:1"

These should be specified in the /etc/vmware/config file on the host.