dpeters is correct. Gone are the days when an analog piece of gear imparted its own character to the PQ. DVRs are fully digital other than the composite/S/component outputs, which means PQ is locked in the digital domain and can't be altered, not for better nor for worse, without puposefully performing a mathematical operation on the binary coefficients that represent that data. Since that does not happen between the uplink and the TV (assuming HDMI input) the DVR has no opportunity to color the character of the video. This is why all DVRs from the Tivo HR10-250 to the HRs to cable DVRs all have virtually the same PQ, another advantage of digital.
There is one known exception, which is that the HR24 uses RGB while most if not all of the rest use Y Pb Pr. Once you un-matrix Y Pb Pr it is identical to RGB, but it has been found that some TVs treat one a little different from the other, meaning that there may be the need for a slight adjustment to chroma or black level to get it to look the same. HDMI is compatible with both, so faithfully transports whatever is used to the HDMI RX chip in your TV. Depending on make and model, this might cause one to look a little different than the other prior to readjustment.