From ldm(1M):
"cpu-arch=generic|native
Specifies one of the following values:
generic uses common CPU hardware features to enable a guest domain to perform a CPU-type-independent migration.
native uses CPU-specific hardware features to enable a guest domain to migrate only between platforms that have the same CPU type. native is the default value.
Using the generic value might result in reduced performance compared to the native value. This occurs because the guest domain does not use some features that are only present in newer CPU types. By not using these features, the generic setting enables the flexibility of migrating the domain between systems that use newer and older CPU types."
Another major feature is SR-IOV support, which can enable bare metal I/O performance for logical domains, read more here: SR-IOV feature in OVM Server for SPARC 2.2
There a new set of patches available to update the system firmware to 8.2.0 which is needed for the new features.