I got the upgrade back when it was available. What a deal it was. Actually, what I did was get the Acurus upgrade to the ACT 3. I was sent a new ACT 3 and was allowed to keep the Acurus. I could also have had the Acurus upgraded, but elected not to spend the cash. From those I've talked to, the Soundstage upgrade is very much worth it.
Now the bad news. After the dealine for the upgrades, I changed my mind on the Acurus and was told the upgrading program was over. You might try just giving Klipsch a call to see. The old Mondial guys are still around and are very helpful. You can also get great customer service from the email addy on the Klipsch website, just make sure you get to the Aragon section.
Good luck.