I wanted to bump this old thread to tell the reason for not being able to resume downloads with user level id (but could do so with root id).
Although I had mapped the drive with gid=users my user belonged in a group of the same name as the user id, not in "users" group.
So, in order to fix this I set the user id's group to "users" like it should be.
I don't know if this is common behavior for all linux distros but at least Fedore core 1 does this->create a new group of same name for the user-id.
So remember to put your user id to "users" group for the above mount command to be effective in aMule's case
Thanks for tips, aMule has worked fine for the last few weeks now.