I'm switching it to an alias now, since we have official confirmation now.
Scans of the official Dengeki Visual Arts magazine are out. This magazine contained all the new information related to the anime, including staff interviews. In the Q&A section there's a question about the cast of the anime and the answer says that only two characters have new voice actors: two characters who were both voiced by Tomoe Tamiyasu. Since the Q&A doesn't mention the change from Miyako Suzuta to Naomi Wakabayashi it confirms they are, as suspected, the same person.
Pictures of the magazine:
http://livedoor.blogimg.jp/otaku_blo...d/7d623d12.jpg,
http://livedoor.blogimg.jp/otaku_blo...f/6fb10c06.jpg
English article:
http://www.animenewsnetwork.com/inte...-busters-anime