I double checked sunsolve to make sure there weren't any patches I missed but I didn't see anything. I would take a look at the source, but it isn't available afaict. The Solaris::Kstat module you'll find on CPAN is for 2.7 and earlier. I once sent an email to Alan for the source but never heard back.
I'd also love to know how he was able to build his source using the mntinfo_kstat struct, since the header file in which it's defined, nfs/nfs_clnt.h, appears to be busted.