I am not sure there is any significant step forward in technology here, other than it appears they have been able to reduce the size of the processor and the overall size of the hearing aid. One would have to see the previous 7Nx generation beside the Signia X to see if the size reduction is of any significance.
As for the use of a motion sensor, this is not new to Signia, and the 7Nx (as well as the Rexton Emerald, and Kirkland Signature 8.0) had it as long as you were connected to an iPhone (possibly Android as well). The hearing aids used the motion sensor built into the smart phone to determine if you were moving. They called the overall system the 3D Classifier. It used Acoustic Information, Own Voice Activity, and the phone Motion Sensor to identify 24 different listening environments. To their credit the default Automatic mode which uses the 3D classifier is pretty good. How much is due to the motion sensor input, I do not know.
This improvement unless it includes something else other than the use of a built in motion sensor strikes me as a lot more sizzle than steak. I suppose it might appeal to someone that does not intend to use a smartphone.