I have not made a "formal" decision on this. I made Demogorgon as a favor for a forum member in another thread. The poster wanted an artifact to weaken Demogorgon for their lvl 20 group and we all said Demogorgon is to weak as is. So I made mythic version that provided an improved (IMO) CR 28 Demogorgon in case that was really all he/she needed and applied the mythic trait to give it the power I feel is closer to what Demogorgon requires. So, to be clear I was not really comparing the mythic version to my previous Epic CR 34 version in terms of power. I just made a new one based on the what I thought the poster might need.Curious, you have made a CR34(?) version of Demogorgon in you Epic Monsters thread. Is the new mythic version CR28 because you estimate that's roughly the same power level? I'm pondering where to place the top tier Demon Lords myself, as I feel the official versions too weak. I was considering just adding 5 to all the CRs (so Demogotgon and Orcus CR31), but maybe CR28 mythic is a better fit?
Personally I like the mythic template a lot and think it is a better fit than a CR 31 version. In fact. I am think of converting all of my epic monsters to this thread and mythic variants when it makes sense. Currently I am thinking something like this:
Demigods (and similar): CR 21 - 30
Lesser gods (and similar): CR 26-30 X 2 (Mythic 1)
Intermediate gods (and similar): CR 26-30 X 3 (Mythic 2)
Greater gods (and similar): CR 26-30 X 4 (Mythic 3)
This would keep everyone in the same bounded accuracy, but allow greater gods to be much tougher. However, it might be a little limiting and perhaps I need to allow for CRs above 30.