For traditional dehydrating, we've been really happy with the model never_retreat mentioned. Ours doesn't have the timer (
https://www.amazon.com/Excalibur-3900-Deluxe-Tray-Dehydrator/dp/B001P2J3K0/), but it's been good.
For any that are curious, we've had a freeze dryer for a couple months now. We've been too busy to use it a ton, but have done 10 or so batches so far.
Downsides:
- Cost. As Mike noted. A "small" 3-tray unit is low $2K, "standard" 4-tray is high $2K, large is near $4K. The trays are also larger as the unit gets larger.
- Maintenance. To keep the price from going much, much higher, the units use commodity HVAC vacuum pumps. As such, to prevent early pump death due to the water and contaminants from the process the pump oil must be drained, water separated out (I freeze it for the purpose), and filtered after every batch. Not a huge deal, takes maybe 5 minutes/batch to swap out the oil, but non-DIY types would not likely be OK with it.
- Batch time. How long a batch takes varies widely depending on what you're drying. 30-36 hours is about the average for me.
- Noise and heat. The pump is decently loud, though several people have made noise-insulating enclosures with fans to keep the noise down. It also puts out a good bit of heat, and can't be placed in a garage if it's hot out, as cycle time increases greatly when environment temps start going over 80-90F.
Upsides:
- Better nutrient retention than canning or traditional dehydrating.
- Better rehydrated textures/flavor (for most things)
- Long-term (~25 years with mylar and O2 absorbers) storage of things that can't really be long-term-stored other ways, or aren't as desirable in other ways. (e.g. yogurt, cheese, eggs, leaner meats, "complete" meals)
If you've ever had the freeze-dried backpacking meals, you'll have a good idea of what the result is like. In general the rehydrated food will have the same texture/taste as if they'd just been frozen and thawed. Some things work well, others don't, some things work well with some tweaks. For instance avocados don't rehdyrate with quite the right texture, but if you powder the result it makes guacamole just fine.
Some people like eating freeze-dried things directly for snacks, some don't. Things like FD'd strawberries, apples, watermelon, etc. I've found people either love or hate, not much in between. Though I suppose that's true of traditionally-dehydrated stuff, too.
