Hello Megan and welcome to the forum. It's been awhile since I myself have posted here. I have three Greys 1 congo, 2 timneh, I got my first grey about 10 yrs ago which was a little Timneh. I don't think the bonding thing is correct, I've had no problems with my greys bonding to me, although I do have a family my birds seem to know I am the bird person...I do all the care giving & feeding, I'm also the only one that spends quality time with them, so I guess they've just naturally bonded to me. I would say greys are generally more relaxed then your too, and the congo's can be more prone to picking feathers over the smaller timneh grey. I don't know which grey you prefer Congo Or Timneh, but I say meet both and see what you think, they have equal qualities. Congo being a bit bigger is going to be a bit louder, although as parrot's go, I believe the African species to be the quietest. Are you considering a older bird or a baby, All my grey's have been 2nd hand birds and I've had wonderful result's. Good Luck
Also wanted to add, congrats on your success with your too, that's great your having good results with feather growth.