My apologies for the length of this post. As anyone in the BR forums can tell you, I'm prone to running at the mouth... or at the keyboard, i guess.
I'm actually doing something similar with a setting I'm working up. (Digression: Unfortunately I can't afford the .pdf right now, so I'm making do with my copy of Blue Rose and hand-written notes about the changes that seem to have been made. From what i hear the Blue Rose Companion will have conversion guidelines, so i'm saving a gift card for that - so if anything I describe sounds wonky, rules-wise, that's why. End digression.)
In my setting, the Shaping Talent feat has been removed, so most heroes can only get shaping powers via Wild Talent; but there are some alternatives.
One hero can take the Arcane Magic feat, which allows him to use Int for all powers (I'm otherwise retaining the power-specific ability system used in Blue Rose), as he draws on his arcane knowledge to devise an on-the-spot spell. This feat has a prerequisite of being trained in Knowledge: Arcana, but also serves as a prerequisite for the Ritual feat (to be taken straight from the BR Companion) and another new feat, Evocation Talent, which is essentially Shaping talent for arcane mages.
Another hero can take the Spirit Magic feat, which allows him to use Cha for all powers, as he compels eldritch and natural spirits to perform services. I'm trying to decide on a good prereq for this feat, but it also serves as a prereq for Rituals and Inanimism Talent, which is again a parallel to Shaping.
A third hero can take the Psion feat, which is the odd duck of the bunch. He still has to use Wis and Cha depending on whether a power is sensory or influencing, but he is able to take part in psionic combat (the version used in Mindscapes and Hyperconscious, from Malhavoc Press; not any WotC version), which has the added benefit of allowing him to recognize any other creature with the Psion feat. This feat also serves as a prerequisite to Psychokinetic Talent, which is (surprise surprise) a parallel to shaping.
Further, I'm adapting the Invocations system featured in MSRD and the Lesser Invocations seen in Modern Magic, to allow anyone to attempt an arcane rite, regardless of role and feat selection. I may also use the various apotropaic rites and charms seen in Modern Magic, and possibly some of the rituals in Malhavoc's Mystic Secrets. The setting is pretty magic-heavy, as you can see.
This all works from the standpoint of setting flavor, and you may find something like it works for you. I'm a little unsure about the balance of those feats, though - Arcane Magic and Spirit Magic give benefits that roughly parallel what I understand the standard True 20 rules already do, but allow an Adept to really focus on a single ability score, as well as providing prereqs to a major magical system ('cos Rituals look to be tres cool). Conversely, Psion keeps the adept sprawled across two or three abilities, and although it grants access to Mindscape-style psionic combat, that's often as much of a risk as it is a benefit; plus i've only got a single follow-up feat so far (although i might adopt some from the psionic SRD to flesh out a full tree).
The fact that each feat i looks at feels like it's not quite as cool as the others, until i look at the others, suggests to me that they're all about equal (but maybe equally underpowered?). So maybe all three need a little extra pizzazz. Additionally, I'm considering turning the three pseudo-Shaping talents back into a single Shaping Talent, and just adding a prerequisite to have one of the three style-based talents. (Which might allow an adept to switch which ability he's using for shaping, in case he's taking ability damage in a fight. Handy? Too handy?)
Feedback on these last few questions would be great. I'm not so fetishistically determined to maintain mathematical balance here, I just want to make sure that all three routes are about equally attractive.
No kitten is going to tell me what to do. I'll fall off this branch to my death if I feel like it!