It would be really cool to have an option to configure PF hoppers to only pick up certain crops, the user could open a GUI, and toggle which crops they want the hopper to pick up. This would be a really cool feature for people who have layered farms, such as I do, that way you could have 2 storages in one chunk for completely different crops. You could further this idea by making it possible to disable PF hoppers from the same gui, so you could manually harvest your farm for a while, without being forced to use /auto or break the hoppers. I think these ideas would be cool to have, and would eliminate the sometimes messy nature of pf hoppers ("Oh, I killed a cow in my base, now there's a random piece of stake in my all-cactus storage") TL;DR : Make it so theres a way to have only certain crops go into PF hoppers, and you could also add a way to temporarily disable PF hoppers.
I was thinking about this a few weeks ago and was going to prototype this but I got busy with the main update! Still plan on playing with this feature as I would love to see it on the server. You also have a nice idea about having them toggle! Maybe I could make a remote for this "upgraded" hopper!