Did you know that William Sofield and Thomas O'Brien opened Aero together? It was there that William Sofield met Tom Ford who tapped the interior designer to help revamp the Gucci boutiques and later designed the Tom Ford boutique on Madison Avenue after opening his own firm, Studio Sofield. Sofield and O'Brien used to both work at Ralph Lauren so it's interesting that Thomas O'Brien's aesthetic remained very American while Sofield's style became much more glamorous and luxurious.
I don't think there is anything wrong with a designer changing or evolving their style. It can happen as one expands their horizons and travels to other countries or is exposed to more expensive materials which is what I assume happened when William Sofield began working with Tom Ford. (I think a person could become more glamorous just by being in the same vicinity as Tom Ford!) I really wish there were more examples of the work on Studio Sofield online. There is a website where I am crossing my fingers they will post their design portfolio because I know there is much more to see!