I'm just in the dilemma of chosing whether to buy a second hand CEVO or a new CEVO...what I know is that I will buy one

Main concerns I would have are:
- Battery degradation throughout the years. They are guaranteed for 5 years so nobody has been able to reach that mark but... have you guys seen any degradation yourselves since bought them? If affirmative is it less range? longer charging times?
- Kms in the ODO: what's the maximum kms you have seen in the Odometer of a CEVO? I'm not concerned here with the autonomy but the number of kms it may last during its expected lifespan or for example 7 years. The reason why I say that is because I've seen one I do like with 6500kms already.
Is there anyway to check the health of a battery? If I buy a Demo C-EVO I would like to know if the battery is 100% in shape but without the OBD interface I don't see how.
Many thanks guys in advance!