Archive and shortcut Tasks using hidden DL in GAL or local Outlook DL

Hi everybody.

I've a customer who's asking how he can use groups in Archive and Shortcut Task without showing the groups in GAL.

Question 1 . If I create a task using a visible DL in GAL and after I hide the DL what happens ? Do I got problems with indexing ?
After a DLC local cache refresh I'll miss the DL ? Could tasks continue to work ?

Question 2. Creating DL in the outlook address book of default mapi profile used by EX I see I could use this DL in task. Because it's a local DL it doesn't appear in GAL.
What are the limits in this case ?
I got correct indexing for all mailboxes which are members of this local DL ?

I checked EMC kb and forum, but I find onlysome notes reguarding problems after hiding jornaling mailbox from GAL, but not info on DL.

Thanks

Andrea