Hi watergirl. We were on Infinity in February 2006, and Century in July 2007. Most of the changes we noticed were in the specialty restaurant -- most obviously, the absence of his signature dishes. Still, all was was superb in both venues.
My husband just mentioned that this was the first time he's seen sweetbreads on the main dining room menu since 1993. But, I don't know if that is related to the change in master chef.