When and why to deprecate filesystems

The documentation is definitely suboptimal. AFAIK, useful idmaping requires krb5. I haven't dug into the details -- this may be a server implementation decision instead of a limitation of the v4 protcol. If krb5 is in use, there is a good chance that UIDs/GIDs are coordinated and idmaping isn't nessicary. I use v4 heavily at my $day_job without remapping without much complaint other than there being no showmount equiv (but I think it so be possible to write a usespacer cli client that does ls on the root export).