First, if you haven't, I suggest reading up a little on passive vs. active PFC, waveform, etc. Second, my (older) CyberPower CP1500PFCLCD works a treat with apcupsd. From what I've seen, at least some newer CyberPower models work, as well, though I don't think there is an exhaustive list anywhere. It looks as though the LE850G uses USB for communication, so I think chances are good it will work.