QGD Exchange Var is a pain for Black IMHO because White can launch a "minority attack" on the Q-side without making any concessions there or anyplace else on the bd, and Black is liable to end up with a backward c-pawn on a semi-open file (semi-open for White not Black that is)
1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Bg5 N8-d7 5.cd5 ed5 is optimal for White because Black's QB is hemmed in by the QN. Of course White can exchange whenever he/she feels like it but if the Black QB isn't hemmed in by Nd7 Black is better off than in the line I give above.
Since your'e a diamond member go to the video library and look up QGD videos and most likely you may find one or more on this exact line.
PS: Do you plan on playing this as White or defending as Black? You might get better answers if you make this minor pt clear.
Ok, these may be some dumb questions, but I havnt played much of the QGD before.
1)Why is the exchange variation so feared and considered critical?
2)Apparently you can avoid it after 1.d4 nf6 2.c4 e6 3.nf3 d5 but I dont understand how, cant white still just exchange?
I could find any exact answers to these after a google search, all the answers seemed somewhat vague.