I have an excalibur with 9 trays. If you spend the energy, why not dry more per batch? You probably also want a set of silicon sheets, but you can also buy cheaper ones in oven size and cut them to size.
I use it for drying edible mushrooms, some edible leaves and making hiking meals. I dry most things at maximum 50C, anything hotter will just taste burned.
For my hiking food, I want to be able to just add boiling water, stir and wait for 12-15 minutes. To achieve this, I must cut all veggies very thin and small, like carrots grated instead of sliced. And I precook most veggies for a short time. If you don't do that, you will need to soak the dried veggies much longer before using in food. If you make lots of slow cooking food, that probably works without precooked veggies. For mushrooms, I don't precook and put them in boiling water for about half am hour before using them in a sauce or in the frying pan.
Stuff like raspberries and small tomatoes take a long time to dry. The fruits are too well packed in a skin that dries out badly. Small tomatoes should rather be cut in 4 pieces.
If I have high things to dry, like leaves that curl up, I use every other tray. So having many trays gives you that option.
I dry tomato sauce on a silicon sheet which I put on a tray with perforated sheet. It should be thickened, cooked in, and smeared out really thin. If you leave a little corner thicker, that part won't dry for ages. When I cook that sayce in hiking food, it turns out very well. So if you grow tomatoes, I can recommend making sauce of them and dry them.