Brammo Empulse was produced in only two versions, which differ in the type and power of the electric motor and the type of front forks. Brammo Empulse R is a more powerful variant with fully adjustable front forks compared to Empulse non R.
Before buying, I would recommend downloading the data from the flash drive under the saddle and analyzing it using a LOG file converter. You will learn a lot about the health of batteries and other electronic components.
It is also important to check that no coolant is leaking from the electric motor. Check it from the outside or after removing the plastic side cover of the engine. Under the cover, everything should be completely clean. Also check the lower part of the gearbox for oil leaks. The inspection of other mechanical parts is the same as for classic motorcycles. I would focus mainly on checking the wear of the chain and both sprockets.
The disadvantage of this amazing bike is that Brammo no longer exists, so it no longer provides any service support.