Oh I see you are pretty new so here's the main link to the Unofficial Service Manual maintained by forum member Brian T Rice with lots of members contributing.
https://zeromanual.com/wiki/Main_PageAnd here is the part about the motors.
https://zeromanual.com/wiki/SDS_Platform/Unofficial_Service_Manual#MotorThe 2014 and 2015 SRs had the surface mounted magnet motors. They would over heat if pushed hard with the larger controller.
In 2016 (the first year for the DSR) they brought out the IPM motor which holds in magnets in place with a cage type rotor and gives more air space between the magnets and the stator coil making it less likely to over heat. The down side is now you have to take the motor (whole bike of course) in every 8000 miles to be commissioned ($50-$100).
The bike's VIN wouldn't show it as a DSR so resale could be tricky and of course insurance rates are higher with an "R" so you could risk
insurance fraud. The biggest issue assuming you buy them new is: $3000ish for the motor, $3000ish for the controller, and $1000ish for a MBB (main bike board) which is the brains of the bike.
You can pick up a used DSR in the $9k-$10k range and some bikes that people need to sale go for less than that.
So for those reasons I wouldn't swap it over.