not really, as long as it is greater than 10dB. The most useful power backoff is in the 1st dBs. Reducing the power by 3dB goes a long way for the network. When PC is reducing power by 10dB, then it means the cell is not interfering with anyone anymore, for sure.
Going beyond that is required when you have tight frequency planning, or to further improve “noise”. That’s especially useful for EGPRS transfers.
a typical BS PWR MIN is around 14dB.
Going too low might slow down HO detection, and might make the radio link very sensitive to any little change.