The BMP085 baro sensor is not necessary for good stable flight. The baro sensor to me is a bit of a novelty attempt at altitude hold which in my experiments so far shows altitude vary +- 5 meters as it slowly senses and adjusts.

The BMA180, while technically not necessary for stable flight, enables the auto-level ability where at the flick of a switch on your transmitter, the multirotor should level off to a pre-calibrated staright and level hover. As I said, not strictly required but good to have once it's setup and calibrated properly.

The only minimum requirement is really the 3 axis gyro and from videos I've seen on youtube, other people are getting quite good stable flight using just the 3 axis gyro. The message that comes through from those guys is that it's really important to have balanced props and motors to get a vibration free frame. Once you've got that sorted, move on to adding more sensors.

Myself, I'm still working on balancing and trimming for stable hands off flight.

Is it the baro realy important to the multiwiicopter? What are the other sensors that we can put on this board? And, are they going to give a more stable flight?

Thanks in advance.