Regarding HammockGear's Burrow Econ.

Can you tell me the difference between a Burrow Econ 30 and a Burrow Econ 40 with 3 oz overfill? I would assume the 40 with overfill might have a higher density than a standard fill 30, i.e. the standard 30 would be taller than the overfilled 40. According to the website, they both weigh approximately the same.

I just got a Burrow Econ 40 with standard fill and it just seems like there is too much possibility for the down to shift and leave empty spaces in there due to the low density of down. I'm considering returning it and getting the either the 30 or 40 with overfill.