Disklavier

Hi folks,
  My battery for my MKIV PRC-100 is on its last leg. I'm looking to replace with a battery compatible with the Sharp EA-BL08 that it came with originally. 
  Are there any issues with using a compatible battery? Also, I see the replacement batteries come in two flavors 1700 Mah & 2000 Mah.  Since the Sharp is rated @ 1700Mah are there any issues going with the 2000Mah.
  Yamaha advised me not to use a substitute battery saying if I fried the PRC-100 it would be $2200 to replace.  Perhaps that's a bit dramatic as I believe the risk is low.  Thoughts anyone?

Thanks,
Steve