I'd think the Debug adapter allows for one to connect the main board (crazyflie) to a secondary board for debugging purposes. I'm not 100% sure though.
I'm looking at this and AutoQuad M4. The M4 looks interesting because it allows the ability to scale from a nano quadcopter to full sized quad with 16 brushless motors. It is also open source. The downside is it doesn't come in kit form and I think overall is slightly more expensive. Not sure by how much because I haven't been able to add up all costs of parts that would create a flyable nano quad. The other benefit of the AutoQuad is it has GPS capabilities for autonomous flight.
I'm looking at this and AutoQuad M4. The M4 looks interesting because it allows the ability to scale from a nano quadcopter to full sized quad with 16 brushless motors. It is also open source. The downside is it doesn't come in kit form and I think overall is slightly more expensive. Not sure by how much because I haven't been able to add up all costs of parts that would create a flyable nano quad. The other benefit of the AutoQuad is it has GPS capabilities for autonomous flight.