I have a couple of old DVXuser Li-ion batteries from my old DVX100 which physically fit my new HPX250 (I made sure with the charging base before attempting attachment to the camera) but I tried one out on a shoot and it powered the camera alright but it seemed like for only maybe 20% of the time I got out of the stock Panny battery. Is there any reason not to use these on the 250 other than the obvious reason that their power-time is next to useless?