I never had the 1st edition and have started a game with a friend of mine. I think the reinforcement / blocking rules are way to harsh on the Yanks. Doesn't make sense to me that a German unit blocking the "A" entry hex by Bech would impact Yank units arriving in entry hex "C" by Beckerich.
I played the first edition of this game many times. The reinforcement/blocking rules keep the Americans from abandoning the approaches to Luxembourg City, at least when applied to the south edge of the map (and those are the most vulnerable entry hexes). Bradley was concerned about that happening. In general I didn't find it too harsh on the Americans as they'll eventually build the forces there to push their way on the map, and the German Seventh Army will eventually get spread out and vulnerable as they try to protect the left flank of the advance.