My wife and I just got back from a trip to Chamonix in mid-March. It was as part of a group of about 110 from the Far West Ski Assoc. organization of ski clubs for western states. Quite a few of us did the Vallee Blanche over the week we were there. The guides kept tellig us that you must be able to ski moguls "with security", i.e. safely. We found the hardest parts were not the skiing, but climbing down and then climbing up at the end. We are not great bump skiers but adequate and are otherwise solid advanced skiers. We went on the classic route which was not hard except for a few long bump runs with one being fairly steep. Some more intermediate skiers I had heard had some trouble woth the bumps and fell a few times. Fortunately no one was hurt. Since the area is remote, the only way to get someoone off the hill taht is injured is by helicopter. One of the ladies that went the same day as us asked to be in a more challenging group. They took a steeper route. I also heard that the route from Italy via Punta Hellbronner at Courmayeau is more challenging. There is a book available in the village at Cafe Press I beleive that showed the different routes.
I highly recommend it. The scenery is spectacular!