Power Talk and Whispered Power I wouldn’t really consider to be well covered in DD, so adding them in would be great.
Daredevil is about story telling and energetic socializing, alongside bold action taking and risk tolerance.
Whispered power is a voice-modulator that increases the quality and impact of soft-spoken language… Daredevil does have voice-modulation scripting, but, if you’re a soft-spoken individual, it’s better to include Whispered Power if you want that effect.
As for Power Talk, that’s a completely different take than Daredevil. Power Talk is like a very light The Will To Power, specifically to speech, and less about the concepts of the 48 laws of power like “never outshine the master” or “there’s no such thing as a free lunch.” It’s all just about how to use speech to develop power and influence - perfect for a DD custom.
With Synergy: Tale Of The Dragon in a custom, I’d say it’d be enhancing, not redundant.
Even if you added Synergy: TotD AND Dragon Tongue AGAIN into the custom, it wouldn’t be redundant, it would just further enhance the Dragon Tongue module within Synergy: Tale of the Dragon.
So don’t worry about redundancy.
Now… do I think that a DD + Syn: TotD + Story Teller module would be redundant? Maybe a bit overkill, but if you work as a story teller (comedian, public speaker, etc.) I think that would actually work really well