We have a ‘bean archive’ in the coffee shop. These are single doses of frozen beans, vacuum packed (in a £30 ish machine) and frozen at a usual -18-20 degrees (ish), 10-14 days after roasting. We’ve been doing this for quite a while now and the main things we’ve learned are:
The whole thing works better if you go straight from the freezer into the grinder. Freezing makes the coffee more brittle, so I suspect it is less stress on your grinder anyhow.
Some people in the industry think that this brittleness leads to more uniform particle sizes, which in turn leads to more even extraction. This is tough to prove but what I would say is that we have used beans close to a year after freezing and they taste every bit as good as when the coffee was in peak condition.
We do grind very slightly coarser for frozen beans and I’m not sure why this happens. We’re talking a small change, a couple of the smaller lines on an EK43. Which at a guess, is maybe less than a click coarser on a C40.
Finally, when we were first exploring this whole area, we used this information from the guys at the Manchester Coffee Archive after meeting them at Cup North years back and having a very excitable (highly caffeinated) chat about it all.