its easy using mdadm, to set up your raid config again but i dont know if it will automagically 'pick up the raid config'. Thats a distro specific question you should ask in the amahi forums.
[ Amahi developer here ]
There are a few ways to add storage to Amahi, however, RAID is done at the distro level -- Ubuntu for the latest release or Fedora for the previous release (and the next one) of Amahi.
In Amahi, you create shares and point them to wherever the storage is -- whether it's RAID, using Drive Pooling (using Greyhole in Amahi) or a local LVM partition or just a regular partition.
As skittle mentioned, mdadm is great, if you know what you want and how to use it.
Thanks for the kind words for Amahi :-)