A couple of other panadapter/waterfall advantages that I neglected to convey on my post above:
In contests, many "big guns" tend to run (call CQ) in the lower to mid areas of that mode's band segment...the crowded sections. And many S&P'ers tend to concentrate around those areas. With a scope, you can always "see" what's happening at the upper, less crowded reaches of the segment's edges...where the "little pistols" (drowned out in the crowds) migrate to try their hand at running. If you spot a new "blip" up there, you can catch/pounce on someone you ordinarily might miss...and it just might be a new mult!
If you're fortunate enough to have the antennas and power, giving you a strong signal that lets you run and handle pile-ups 95% of the time (especially in a rare country, or states like Wyoming or the Dakotas), even if you're not using your panadapter, they can be indirectly beneficial to you. The S&P hams using *their* scopes can see your huge "blip" and migrate to you over other smaller blips, thereby helping to sustain your run.
And obviously when working a split-frequency DX operation, where they say "5 to 10 up", many times you can "see" the station's blip that immediately responds to their call (if the other stations shut up

), so you can move to that frequency, or note the trend of their tuning.