Exactly what was changed in the Spark aircraft firmware from version 01.00.0900 to 01.00.1000?
https://www.dji.com/spark/info#downloads Spark Release Notes PDF does not provide this information.

Thank you for reaching DJI forum. For the latest update of spark, we optimized  the Spark remote controller for you to use an OTG cable for Android devices. For the upgrade of the aircraft itself, we don't  have a new specific feature. What I know is we need to upgrade the aircraft as well to make sure it will synchronize to the new update of the remote controller.  Don't worry, I will clarify this to our R&D engineers  just to make sure.  I will notify you as soon as I receive a response from them. Thanks for you understanding.

DJI Paladin Posted at 2018-10-3 04:07
Thank you for reaching DJI forum. For the latest update of spark, we optimized  the Spark remote controller for you to use an OTG cable for Android devices. For the upgrade of the aircraft itself, we don't  have a new specific feature. What I know is we need to upgrade the aircraft as well to make sure it will synchronize to the new update of the remote controller.  Don't worry, I will clarify this to our R&D engineers  just to make sure.  I will notify you as soon as I receive a response from them. Thanks for you understanding.

Thank you, DJI Paladin.
I don't see the connection between an OTG cable and the aircraft itself.
How long do you think it will take to get an answer?
In previous inquiries of this type more information has never been returned from the "R&D engineers"

Chuck101 Posted at 2018-10-3 04:12
Thank you, DJI Paladin.
I don't see the connection between an OTG cable and the aircraft itself.
How long do you think it will take to get an answer?

To be honest, I don't have a specific time frame for the response from our engineers. The good thing is your query has been forwarded to them and I will give you the answer as soon as possible. Thanks for your patience.

Chuck101 Posted at 2018-10-3 04:12
Thank you, DJI Paladin.
I don't see the connection between an OTG cable and the aircraft itself.
How long do you think it will take to get an answer?

I received the response from our engineers and as per them, there's no new feature or function that is added to the AC. You can choose not to update the AC to the latest firmware  and it will still work fine.

DJI Paladin Posted at 2018-10-9 06:55
I received the response from our engineers and as per them, there's no new feature or function that is added to the AC. You can choose not to update the AC to the latest firmware  and it will still work fine.

Thanks for reporting back.
Even so, they would not tell you what the purpose of the update was for?

somewhere after .701 they have corrupted something with compass calibration/declination/stabilization   

many reports here of sparks not aligning properly and pointing differently than the flight computer thinks they are pointing .. resulting in the spark flying RTH cocked off to the side, not landing facing they way they took off and potentially dreaded fly aways if the GPS/IMU/Compass disagree enough to give it fits...

both my sparks were flying great under a factory loaded .701 both are flying terribly now under .1000

also noticing more motor noise and worbal in decent ... less stability and very noticeable counter banking and other weirdness in the camera gimbal  flying sport FPV .. in .701 the FPV would bank with the drones bank properly .. now, especially in right turns.. the camera banks left then jerks to a right bank.. and yes.. the  turns are coordinated and not slipped/skid..

have asked numerous times for them to check this..