In my experience it looks like being able to get it working correctly depends a lot on the specific hardware you're using, which personally I think is fairly useless.
I spent several weeks trying to get IDR working through 10d SBS, rebuilding the server from scratch several times after each restore attempt hosed the servers setup. I had several people from both Microsoft and Dell in contact with me trying to work out what was causing the problems and how to resolve it without success.
In my case the restore would never work because the process would fail to load all drivers for all the hardware in the server, regardless of how to tried to do it. So what I ended up with was a server which would either recognise the RAID-5 HDD array but couldn't access the tape drive, or would recognise the tape drive but couldn't access the HDD array!
