Personally? I would shunt it back up to full BaB. It would actually start closing the gap (slightly) between Dragon Shaman and the ToB classes (as well as some of the PhB classes.

Some auras, i.e Insight, are completley useless. Maybe it would be good if you could upgrade auras at higher level. For instance, if you were at a high level, and you had taken insight previously, it would allow you to use true seeing once per day.

My advice, take it as you will. Good job so far!