have you ever tried making molten chocolate cake with no yolks?
i have this recipe that calls for two eggs and two egg yolks over equal amounts (150gram) of chocolate and butter (along with some 4.5T sugar and 2.5T flour).
this recipe is rediculously simple and turns out delicious. but seperating the eggs is a pain and i end up stuck with eggwhites i never use (no, not even for maringue or an eggwhite omelett :)
would you REALLY tell the difference if i omitted those and just use two eggs instead?
as far as the egg whites go, i can understand your desire not to be wasteful as justification for omitting the extra yolks, but do you really see separating 2 whites as THAT much of a nuisance? it's a small price to pay for such a delicious result.
and yes, you will notice a difference without those extra yolks. you're altering the ratio of wet:dry, and omitting a crucial ingredient that contributes to the richness & creaminess of the center.