Looks like both of your formulas are the same?
To your question: this may be a lot of fun to play around with, but it will costs hundreds of dollars per month to leave on 24/7. For comparison: that power is more than what it would take to blast your AC all month in the summer.
If you search you should see the error only effects a few features and not all of iLO.
And iLO is needed the same way a homelab is needed. sure is nice to have though
Plus hardware pass through makes moving VMs more complicated. More virtual disks and networked storage for everything reasonable
I have not found L2 ARC to be much of a benefit for most of the time.
How many disk bays does the system have and how much storage to you need?
May not be a bad idea to make an HDD pool as large-volume backup target and a an SSD pool for data you want to store and access remotely
buy an ancient/“for parts” 1u 24 port switch and take the guts out. 24 port so you have enough blank space on the face to cut the USB ports
What’s your budget?
If you can, spend an extra ~$100 to get at least an R730 imo. You will get more performance and the $100 will pay for itself in power savings in less than 1 year.