Aww that is so great!!

I have a couple of cockatiels like that with a similar story. They were basically neglected and cagebound but in the 7 months that I have had them, they seem so much happier. They hang out outside of their cage much more often, and interact with my other cockatiel. My male sings all the time, and though I work with him often, I know that he will probably never be hand tame, and like you that is alright by me. The female is partially hand tame, she won't very willingly step up onto my hand while she is close to her cage, but once she is away from her cage and her mate, she is just the sweetest!!

Good luck with your birds! I think that birds are totally awesome. They have such unique personalities and can be such clowns sometimes in their own right. And I also believe that animals know when they are loved, even if they don't show it. Kudos!!