I'm having the same problem, with the following setup:
Version Information:
Your Joomla version is: 1.0.11
Your SMF version is: 1.1 RC3
Your Joomla-SMF version: 2.0 RC1
Latest Joomla-SMF version: 1.1.4.2
What shows up when i try to change a name via the profile tab, when accessing the forum in wrapped mode inside Joomla!, is:
~~~
FROM::/home/*mydomainhere*/public_html/*mysubdomainhere*/joomla/administrator/components/com_smf/admin.smf.(there has to be something here, either class or html but it doesn't show)
|| getjid || 1538
A [not so weird] workaround is running SMF standalone, changing the name, then running Joomla's administration, and changing your name there too, via the User Manager. But that's not what it's about...
Cheers,
-Sino.