I don't know if Dave has any experience with 1,1-DIFLUOROETHANE as a "preservative". I certainly don't. There are some reasons I would avoid it--although as I indicated I do have a can of it in my computer supplies.
The problem I see is getting rid of the oxygen which is in the can--do you pull a vacuum, and then replace that with some inert gas? How much "flooding" with the 1,1-DIFLUOROETHANE does one have to do, to displace a significant amount of oxygen? I don't know. It is denser than air. My refrigeration experience is mostly with R 12 and R 22, in building refrigeration systems for boats back a few years ago. Although I had large amounts of both polyester and epoxy resin, I never used any gas to store it.
1,1-DIFLUOROETHANE, is inflammable. It can be explosive: (LEL/UEL 3.9% / 16.9%. ) Burning it can produce both hydrogen fluoride and phosgene-- extremely toxic substances. Direct inhalation of concentrations of the gas is often fatal and there are a number of recorded deaths from "recreational' inhalation--thus an agent is added to the gas in the "Dust off" called a "bitterant" to make the gas less palatable to inhale.
If you want a relatively in-expensive source of inert gasses: "Private Reserve" is a combination of Nitrogen, CO2, and Argon used for preserving wine--from about $8.25 a can. I have not used that either...but it seems a more sensible way, than using a potential explosive and toxic gas. Also bottled nitrogen is available from welding supplies some tire stores, and paintball nitrogen tanks (but check to see if air or nitrogen).
Although the "breath" method only reduces the oxygen by 25%- I have used it and keep gel coat in a refrigerator, away from light. I suspect if I really wanted to extend it further, I would go to the nitrogen/combo--or perhaps pure nitrogen....but probably not 1,1-DIFLUOROETHANE.
Here is the MSD