SDS200 has an internal preamp that Uniden have set to as much gain it can take before getting into overload issues. You can hear that the audio from the SDS200 have some ticking gunshots that indicate it is close to its 12db/Sinad level where you measure its sensitivity. It's at -118dBm. The 8600 have no such gunshots and are at -114dBm, 4 dB more sensitivity. Use all features in the Icom like its Noise Reduction to improve the sound quality. What will really show the difference are if you have interferences from a nearby transmitter, that will not affect the 8600 at all.
Icom IC-R8600 is a world receiver which decodes audio channels solely while Uniden is a scanner which decodes radio system. Icom has RF gain to boost the signal but it has no DMR and Nexedge. Most communication frequencies appear in between 100 and 1200MHz. You probably won’t receive any audio transmission beyond 1200MHz!