Some of the digital control sites insist that good digital control can be achieved by less parameters being sensed (gain only). Sensing typically causes additional losses/costs. For me, there are four rules of "closed loop" compensation:
Digital control solutions vs. analog control solutions?
1. Present the highest gain at DC to present the highest output regulation accuracy.
2. Phase margin: never go above 345 deg for transient stability.
3: "Excess phase" - one decade above the output filter pole there can be a -90 to -180 degree phase lag (with a closed loop starting point of -270 that only leaves -45 deg). Phase boosting must be provided.
4. Gain Margin: Whenever the gain is greater than 1, make sure that your phase is away from -360. Sometimes ESR and parasitic elements caused zeroes - pay attention to those.
I disagree with the digiofiles about ignoring phase by only measuring the slope of the gain curve. It is true that there are dependencies between the two, but it could also cause instabilities, caused both by computing latencies and resolution, that could cause problems. Phase ultimately causes instability, regardless of gain.
Both systems should be measured by a network analyzer, such as Ray's. Both are "black box" controllers and should perform similarly under analysis. There are, of course, non-linear digital transient algorithms, which can be examined separately.