Right. Well as you know the camera itself is going to be heavier than the D50. Lucky for you I have both cameras right here in front of me, so I can say that for sure. Naturally adding the grip also adds to the weight, but conversly, it also adds to the balance. it enables your hand to grip a slightly longer area without your fingers falling off the end, and adds bottom heaviness to the camera. So although it is heavy, you should be able to balance the weight if you're shooting with two hands. The AA batteries are also heavier than having any of the Li-ion batteries.
Adding an SB800 with 5 AAs onto the top of that really does make it rather heavy, but I can deal with it. As you mentioned, you might not like to. I think the bonus of having the portrait orientation functionality far outweighs (as it were) the problems of over-heaviness, but that's just my opinion.
HTH
Jack