I'm starting the adventure path this week and I plan to throw in some mythic with the minor runewell once the players get there, but I hope to re-flavor the mythic rules somewhat.
Things I'm considering:
1) Doing away with the paths and aligning the abilities in seven categories, one for each sin.
2) Mythic power use is accompanied by glowing Thassilonian runes displaying on the skin or in the air around the PCs
3) Tracking mythic point expenditure totals as a corruption score for each PC. Higher scores leading to mental anomalies, physical mutations, or susceptibility to sin-based magic or items.
Does this sound doable? Do you have ideas on expanding this?
For the third one: In the appendices of the Rotrl Anniversary Edition there is a char for keeping track of something like that. As for what happens with the corruption itself, you could always impose penalties on the player equal to their corruption (or corruption /2 rounded up/down/whatever whenever something aligned where their corruption affects them.
Additionally, you could have a good side version of it too for the virtuous, where they instead get bonuses vs those corrupting influences. If Dark-side = profane, Good-side = Sacred maybe?.
For example, a Wrathful Person might have to make a check to not kill an enemy they have a grudge instead of capturing them. And to resist Rage-related effects.
A Lustful person might have to make a check vs charismatic people of their type/subtype to not have an urge to get into bed with them. And penalties vs spells like Unnatural Lust/etc.
And so on and So on. All sorts of things you can do with it that way.