I never needed it. Maybe I would have used it if I had found it with my "no buying from merchants" character but I never got too far with him. I just sold my chems for cash on most of my profiles.
I love that armor. "Time to kick some ass!" Although I'm still waiting for it to say something like: "I don't know he's kind of big... maybe we should just run away?" or "God that rifle makes my ass look fat."
To be honest I never wear power armor in FO3. It doesn't give a lot of benefits imo. I'm quite content wearing my lucky sunglasses, my shady hat and my regulator duster or Reilly's rangers combat armor.