Is there any active ham these days who has used a panadaptor (bandscope) and would part with that feature?
Seems unlikely (maybe someone would give up a small built-in LCD panadapter but it's hard to imagine giving up an external panadapter on the type of displays normally used with computers).
One obvious benefit is to spot signals on bands with rare openings such as 10 or 6 meters. With the IC-7300, for example, you can see an entire 1 MHz of activity at a glance. On HF the bandscope is an essential tool for finding the subject of a pileup, or for locating callers when the DX station's frequency is known. During contests I tend to tune more with my eyes than my ears using my Flex-5000. And now with the IC-7300 these very useful features add almost nothing to cost.
On a SDRPlay with free HDSDR software you can see an entire 8 MHz
of activity at a glance while tuning from 100 kHz to ~2 GHz.
Of course, unlike the IC-7300 and Flex-5000 you can only receive not transmit but for $150 it's still a pretty good deal.