One very important consideration of their 1 day processing time, and a key reason why I'll be interested to try them in a future farm:
When I'm going for "optimal" play and I have no particular challenge run or theme I'm going for, my general goal is to have at the beginning of summer 25 quality sprinklers, the desert unlocked, and 80k on hand for 200 Starfruit seeds. By the time they come to fruition ideally I have gotten another 80k on hand and have built 25 preserves jars. I start processing them all (it takes a while) but by the time the second batch has finished growing and being harvested I've guaranteed hit farming 10 and can start selling the preserves with Artisan, gaining 868000 from the summer crops alone by the time the processing is complete. Not bad for year 1.
The main trouble is, first, those are hard targets to hit, for me at least. Unless I'm *really* focused it's tough, especially with other considerations like the community center and festivals and all in play, and I often miss those targets to varying degrees. Second, even if I hit them all the idea of getting *more than* 200 starfruit for the 2nd batch is virtually impossible, even if I've doubled the quality sprinklers by then, because I can't afford them and the first batch won't finish going through the preserve jars in time. So in order to account for any misses, as well as any expansion in my quality sprinklers, I'm typically selling a fair amount of the initial starfruit batch "raw" (which it is better to get more seeds in the ground, ultimately, but it hurts).
With even just 15 dehydrators you could in a day get 80k worth of profits from 75 of those starfruit, and since it only takes a day you have time to process them, sell them, buy the starfruit seeds and get them in the ground in time for them to finish before the end of summer. That means you can get *way* more in the ground for the 2nd batch, ultimately resulting in much higher profits.