5 albums of "powerdowns," seems to be overkill. Especially when the most useful type of powerdown seems to be the very dark, sub-drop. Choose among 22 that vary in attack, length, speed and type of arc from Powerdown:Sub-drop.
Powerdown: Edge provides 17 more options that will get a bit more in-your-face.
Powerdown: Specialty includes a wide variety of drops. The cue titles will tell you most of what you need to know about these options. Rumbler, Over the Cliff, Wind Power, Sine Slowdown Doppler; all have more upper frequencies in them which gives them their character.
Powerdown: Hits adds a very short landing zone by clamping, hitting, or leaving an ambience.
Powerdown: Cues goes one step further than the hits. Each of these powerdowns falls into a cue that might be useful with or without the drop. Again, look to the titles for a pretty good understanding of the cues.