I have a large free dryer with an oil free pump. We put up about 2500 eggs last fall/winter. I freeze dry a LOT of food. From fruits, veggies, casseroles, chili, refried beans, avocados, meat sauces, herbs, etc...my daughter in law even freeze dried some of her breast milk. It is a wonderful tool. Because we have a large, we did have to install a dedicated outlet, but it really wasn't any big deal for us, and I don't think that it raised our electric more than $50-75 a month even running it constantly.
Many things, such as eggs, refried beans, avocados and tomatoes, just to name a few, can be powdered, and takes up very little space in storage. You would likely want to pack those in small mylar bags for long term storage, or pack them in canning jars. I use desiccants rather than oxygen absorbers if I’m storing them in canning jars (shorter term storage).
The disadvantage of having an oil free pump is that you will need to have it rebuilt at some point. Some say after a year of heavy use, but we haven't had to have ours rebuilt yet. It's a pain because you have to send it back to Harvest Right and it's a bit expensive for the shipping and for the rebuild. I would really recommend the premier pump.
I've heard lots of people who've purchased the small, say that they wish they'd have gotten the medium. However, the new small is very close to the old medium. If you can afford to get a freeze dryer, I would highly recommend it! You can put up a lot of long term food stocks in a fairly short amount of time.