Sharing/local roles and acl_users folder for respondents

[fredvd]

Hello,

I'm testing PloneSurvey for a customer on Plone 3.1 and have stumbled
on an issue with the sharing tab. PloneSurvey has a local acl_users
folder for storing local respondents, but this blocks the assignment
of 'main site' local roles on the survey in Plone 3.

Is this an indentional side effect, or is this a Plone 2.5 -> Plone 3
compatiblity issue and did it work on 2.5?

Thank you,

Fred van Dijk