You should have no problems with that cabin. As people have indicated, the Grand Foyer is where people congregate for things such as business transactions, or maybe booking shore excursions. It is definitely not that big a deal. I have also been in many areas of Celebrity ships and except for the rear rooms on the Century class ships, which are prone to vibration, I have never had a problem. I have even been directly below the casino. The rooms have very good insulation.
One other point - I have been on 18 Celebrity cruises and have yet to be on one that wasn't booked up with a sign indicating that no cabin changes would be allowed. So please don't count on that - it is rare. They also would not upgrade you for nothing - unless you had a real issue with the cabin and there happened to be a cabin available, you would definitely need to pay the higher rate - the time of sailing rate by the way, which would be sky high.