I am of the camp that Doom's level of play since his torn pec has been pretty much equivalent to what Phillips is now providing. Doom feasted on poor quality Tackles and end of game sacks (when he didn't have to worry about any threat of the run). To my eyes - he completely disappeared for very long stretches at a time his last 2 years in Denver. The only thing he maybe did better than Phillips was the strip-sack (which, admittedly, is a big play). But - Phillips seems to be stronger against the run.
It will be interesting to keep tabs on the comparison as the year goes on, and particularly now that Phillips has Von on the other side to take away some attention (but maybe Von also steals some sacks by getting to the QB quicker).