IntuitLink (I use it with standalone PS Pro) is just a portal to exchange files and send notifications.  The only thing Intuit Link really retains is the primary email address....   (i.e. client uploads data... when complete I upload returns, invoice, etc...)

That said,  banking info and (Sch D) brokerage info, carryovers, etc., is retained by the ProSeries program and transferred each  year when you transfer the client info to preparer the ensuing years return.