Recently I tried to import OVF template that was created in ESXi 5 into older 4.1 server.
Import failed with the following error message:
Unsupported hardware family
Solution is posted here (http://communities.vmware.com/thread/321314): replace vmx-08 to vmx-07 in .ovf file.
However to be able to successfully import template after such change with ovf tools, you’ll need to use –skipManifestCheck parameter to skip validation of OVF package manifest. Otherwise you’ll get an error saying that template is corrupt.
Same approach works if you need to move VM files between 5.0 and 4.1 server. Before you can turn it on you need to replace version 8 to version 7 in .vmx file (4-5 occurrences).
Unless you use any special features of vmx-08 hardware (ex. 1TB disks), this trick works just fine.