I've been working on this over the past few weeks with the help of some folks at my company as well as the tools previously published by /u/SirMaster on reddit and WintelGuy (https://wintelguy.com/zfs-calc.pl).

I also included a detailed write-up so users can understand some of the overhead ZFS introduces.

I plan on improving the tool to allow for custom drive sizes and vdev layouts but I wanted to share my results thus far.