Understood I must have the same users.
I have uploaded attachments for one or two users but it was a special case where the file was around 9MB and was a temporary situation.
Like I said though you could create say a user2 group and set the file size larger. If it becomes one or two users that need bigger files then you could add them to user2 group in the control panel. Or use the auto promote feature based on post count in the control panel.
