Will grey yolks effect the taste of deviled eggs?

Not at all....It happened to me a couple of times...They will taste just as good............

Here is a great recipe for HB eggs, it's actually Julia's recipe, it's a little more work then just throwing the eggs into some water and boiling them; but the end result are perfectly yellow yokes. 1 large pot w/lid 1 large bowl of ice water (use plenty of ice) 1 dozen eggs 4 quarts of water (start with cold water) You'll need to prick the large end of the eggs with a pin, (I use a bulletin board push pin) don't be afraid to push the pin in at least 1/4 inch. There is a small amount of air that is in the large end of the egg, by pricking the eggs you allow this air to escape. The air is part of the problem that turns the yokes green or grey, so don't skip this step!! Place the eggs in a pot big enough to hold them and the water. Carefully pour the water over the eggs. Place the pot uncovered over hight heat, bring the eggs just to a boil. Once the eggs come to a boil remove them from the heat and cover them for exactly 17 minutes. Remove the eggs and place them into a large bowl of ice water for 2 minutes. While the eggs are chilling bring the pot of water back to the boil. Take the eggs (6 at a time) and submerge them into the boiling water for 10 second. Then immediatly place the eggs back into the ice bath. (gently crack the eggs in several places before returning them to the ice batch) Do the same thing with the remaining 6 eggs. Let the chill for 15 or 20 minutes and peel them under cold running water. They can be kepted in the ice bath in the fridge for a couple days. Trust me this works!!!!

They will be okay ...but, to me, a boiled egg which has been cooked too long is rubbery. The taste will be the same but the texture could be affected. I really like my deviled eggs light and fluffy. I like for my eggs to cook no longer than 13 minutes.

If I were you I would eat one of the eggs and then decide. If it tastes fine to you...then it will to everyone else.

edited to add: I just ran across this bit of information;

You should not boil an egg never more than 20 minutes because its proteins are broken down releasing sulfur, which gives a greenish color to the outside of the yolk and is (slightly) toxic.

they shouldn't taste any different. just put some paprika on them and nobody will know they turned a little gray.

no it shouldn't, that happened to me a few times and they tasted the same :)

no they will taste great