I was waiting for some more replies, but it didn't happen, so... 🙂
After some thought I decided to go with consumer motherboard, my Unraid box will be in a separate room on a shelf with some old LCD and keyboard and mouse connected. The idea for this box is to run unattended 24/7, so if I would need to connect to it often with IPMI, that would mean it is not doing what it was supposed to do. I can also get consumer parts for cheap and if I ever change my mind I will go with server motherboard then.
Thanks for your replies.