I agree that quiet kills. But, I can also say, without reservation, that my first few compounds that ranged in speed from 180-220fps were louder than my last 5 or 6 that chrono @ 285-300fps. Granted, the older models had only rubber catwhiskers for noise/vibration reasons. Technology has come a long way in this department.
IMHO, arrow speed plays only a small part in preventing a deer from jumping/ducking the string. Much more important is a quiet bow, and NOT shooting at a wired deer.