Both groups I work for use Arbiter - it has been great for me as an umpire, but I have no idea how it works for the assignor side of things. I used to work for the same group as JRutledge where it was all email based, which I never had issues with, but after using Arbiter I much prefer it.
My grandfather used to assign HS basketball all via paper contract until a few years ago. If I remember correctly, there was no email communication. After the contract was signed, it was all phone-based. I'm sure a lot of people hated it, but it worked for him
