Alright. I work with robitics and a lot with IMU stuff.
IMU stands for "Inertial Measurement Unit" and is a small electronic component that records the foces being acted upon it. It usually consists of acellerometers, gyroscopes and sometimes magnometer (a magnometer measures it's relation to true north).
So the recording of the lean angle comes from the IMU, here the IMU is the sensor. That is why they stress that the installation should be done right (or else you prob could display something like 88deg lean haha). Since the lean angle data in newer panigales is used as input to determine toruqe out on the back wheel (ecpecially if you have the DTC EVO upgrade i.e), then what the lean angle is, is important.
The IMU would also have the possibility to record heavy breaking, or acceleration, and it can be that the electronics uses this data in some way, I don't know.
As a standalone part of a electonic chip, IMU's are really cheap. You can buy them inmany maker electronics stores, for example
here.
IMU's operate on different Degrees of Freedom (DoF). A 3DoF IMU can record forces in three axis. Regular in newer robotics applications is 9 axis. I assume that the newer IMU's on the panigales maybe have more DoF's that the earlier once.
So then does it (different DoF's) matter? No, if the ECU does not use the additional information from the additional axis, recording of forces in more axises is completely irrelevant.
But Never IMU's are probably more precise. Assuming that the measurements are more precise, will such a IMU be a reasonable upgrade? No imo wasted money. We are talking about a motorcycle here, there are a lot of other factors affecting the accuracy of the measurement (in a bad way). I don't think there would be any difference for the rider with regards to more accurate measurements.
It could be that newer IMU's are more reliable and less faulty (the most probable assumption). In that regard, I haven't heard of any problems with the IMU other than installment issues (which has nothing to do with the reliability of the IMU).
So in conclusion, if you have the DTC EVO electronics upgrade and you really really use that to it's max, then prob go with a 2017 or newer IMU if you really want to change it. But I wouldn't, imo it is really a waste of money.