AFP automount sharing broken in Lion Server?

Question

Network rundown:
Mac Mini running Server
two MBPs (one upgraded to Lion, the other still running Snow Leopard)
The Mini is the OD Master for the three Macs and runs a number of services (Mail, Web, Wiki, VPN, etc.). The important service for this thread is that it serves out three shares via AFP, configured to be automounted on the two laptops. Normally all three shares are set up (via Workgroup Manager / Directory Utility) to use the Kerberos v2 UAM; however, for testing purposes I've temporarily adjusted the UAMs as follows:
/Groups -> afp://myserver/Groups
/Volumes/Attic -> afp://;AUTH=No%20User%20Authent@myserver/Attic
/Volumes/Multimedia -> afp://;AUTH=Client%20Krb%20v2@myserver/Multimedia
When the Mini is running Snow Leopard Server (10.6.8), the automounting behavior works as expected when connecting from a laptop without a valid Kerberos ticket:
lionmbp:~>klist -f
klist: krb5_cc_get_principal: No credentials cache file found
lionmbp:~>ls /Groups
ls: Groups: Invalid argument
lionmbp:~>ls /Volumes/Attic
[snip - file listing]
lionmbp:~>df -h /Volumes/Attic
Filesystem                                Size   Used  Avail Capacity  Mounted on
afp_000000004oMw0oYHtK4AvcMP-1.2d00010a  466Gi  277Gi  189Gi    60%    /Volumes/Attic
lionmbp:~>ls /Volumes/Multimedia
ls: Multimedia: Invalid argument
and then with a valid Kerberos ticket:
lionmbp:~>sudo umount /Volumes/Attic
Password:
lionmbp:~>df -h /Volumes/Attic
Filesystem    Size   Used  Avail Capacity  Mounted on
map -static    0Bi    0Bi    0Bi   100%    /Volumes/Attic
lionmbp:~>klist -f
[snip]
Sep 19 23:27:17  Sep 21 23:27:17  FPRIA  krbtgt/DOMAIN@DOMAIN
lionmbp:~>ls /Groups
[snip - file listing]
lionmbp:~>ls /Volumes/Attic
[snip - file listing]
lionmbp:~>ls /Volumes/Multimedia/
[snip - file listing]
However, after upgrading the Mini to Lion Server (10.7.1), attempting to automount the same shares does not work at all, regardless of whether a valid Kerberos ticket exists or not
lionmbp:~>klist -f
klist: krb5_cc_get_principal: No credentials cache file found
lionmbp:~>ls /Groups
ls: Groups: Authentication error
lionmbp:~>ls /Volumes/Attic
ls: Attic: Input/output error
lionmbp:~>ls /Volumes/Multimedia/
ls: : Invalid argument
lionmbp: /usr/bin/kinit
[snip - provide password]
lionmbp:~>klist -f
[snip]
Sep 19 23:15:09  Sep 21 23:15:09  FPRIA  krbtgt/DOMAIN@DOMAIN
lionmbp:~>date
Mon Sep 19 23:17:03 CDT 2011
lionmbp:~>ls /Groups
ls: Groups: Authentication error
lionmbp:~>ls /Volumes/Attic
ls: Attic: Input/output error
lionmbp:~>ls /Volumes/Multimedia/
ls: : Invalid argument
Anyone else encountering the same issues with AFP on Lion Server? Is AFP simply broken, or is there some poorly documented configuration/troubleshooting procedure that can resolve this issue?
Notes:
I only tried the automounting from the Lion MBP, I would expect that a Lion <-> Lion AFP connection would have fewer issues than Snow Leopard <-> Lion
The issue originally presented itself several weeks ago when I atttempted to upgrade the server; this AFP problem was a showstopper so I restored SL from a backup. I have since been testing by cloning the server drive to a USB drive, booting from it, and running the upgrade there.
In performing the Lion Server upgrade, I follow all the defaults. The server is booted off the USB drive to ensure it is in a working state before starting the upgrade. The only post-upgrade changes are to run Software Update (mainly to capture the recent security update) and then to follow the single signon instructions posted here

Answer 1

Some more testing hints in the direction of the problem:
aragorn:~>kinit -l 48h -r 48h -p -f [email protected]
[email protected]'s Password:
aragorn:~>klist -fCredentials cache: API:1501:10
        Principal: [email protected]
  Issued           Expires        Flags    Principal
Oct  1 17:05:53  Oct  3 17:05:50  FPRIA  krbtgt/[email protected]
aragorn:~>ls /Volumes/Multimedia
ls: Multimedia: Invalid argument
aragorn:~>mkdir /tmp/test; chmod 777 /tmp/test
aragorn:~>sudo mount_afp "afp://;AUTH=Client Krb [email protected]/Multimedia" /tmp/test
mount_afp: AFPMountURL returned error -50, errno is -50
Looking in MacErrors.h reveals
paramErr                      = -50,  /*error in user parameter list*/
That both ways of mounting AFP seem to be complaining of argument/parameter errors indicates something isn't being passed across the network correctly or is not being parsed properly on one end or the other. At the moment my dtrace-fu isn't strong enough to delve into this more deeply.
With 10.7.2 due out soon, I think I'll wait to see if Apple engineering caught this already. If not, I'll raise a bug ticket.