It's neat but, for my part at least, the major problem with devil tyrant comes from the DF side.
Humanoid diabolic transformation is a throughly poisoned well belonging to the fallen. I can't look st it without seeing dime store Denarian regardless of how cool a particular design is, and that reaction seems reasonably likely to come up to a tiresome degree in character too.
To a certain extent I don't care about the mechanical benefits of taking it, because it plays on claimed thematics we aren't going to be able to hijack until we're practically in the end game already.
You're basically pulling the rough equivalent of porting over the omnissiah to canon exalted as an active god; there's too much overlap with autobot for people to take your claims of not being his store brand cousin seriously.