Just an FYI on personas. The rarity of them increases the stats they provide to a pretty absurd degree.
Thoth has great skills but as a purple he's providing a pitiful amount of stats compared to Hell Rider. Looking at the diamonds from previous ranks and they're still mogging Thoth despite being limited to 15 levels below his max level.
I think it's still worth because of the skill quality, but maybe something to keep in mind