I think the real question is: Is SMB1 less secure than NFS?
A third way to do this with NFS is to forward the TCP connection over stunnel, ssh forwarding or other similar thing.
I like Kerberos a good bit and I think the complexity of running an LDAP/Kerberos infrastructure is greatly over estimated, but it is disappointing that none of the theorized alternatives ever really appeared. Last I read, LIPKEY was the only serious contender and there were some security concerns that got it nixed.