Did exactly that a few days ago (looked better than I played sadly). Got those almost as soon as they were released since I play on clay a lot and love B7s. This also very well may have been the last chance to get those for that surface. Felt a bit lighter imo.
Looks like he keeps changing between the two. Maybe he's still trying to decide. Adidas realesed two Novak pros since his first GR7 video, so the whole situation is extremely weird. Looks like no one apart from the people on this forum noticed the change, but I guess it's not that surprising considering the reporters asked Berdych about wearing Novak pros only after their match at Wimbledon.