I have let these pillows sit for the recommended 48 hours (they have, in fact, been out of the bag for considerably more than 50 hours), and have also tried to fluff them up as directed.  But they are still pretty flat and weigh considerably less than the 8-year-old pillows they were bought to replace.  And I'm not sure where the "jumbo" comes from.  They're not overly large.  Just pretty normal.  I'll use these for the guest room or maybe even to fill decorative shams, but I will definitely be keeping the old ones for my bed.  I'll just have to keep looking.  It's too bad I can't take the 4 pillows I bought and turn them into 2 (or even 2 1/2).  Then they might be firm enough.  

Pros: Lots of new feather pillows have a weird smell; these don't.
Cons: They are not even remotely firm; all the plumpness is air.