All of that is irrelevant to my suggestion. If RSSI reads in 10dBm increments vs 1, it's much harder to evaluate the efficacy of various filter settings on dealing with adjacent frequency interference. If the hardware supports it, it's worth doing for that reason alone, regardless of any other considerations.You can't use a SDS scanners RSSI reading for any serious work.
I monitored a frequency in the 400Mhz band with a signal of -100dBm, just a little noise in it so it can be heard if the sensitivity changes. I used the filter set to Off, which is the standard symetrical filter used in any other scanner.
I injected a -50dBm signal and at a frequency 7MHz lower than the monitored one. The RSSI changed from showing -100dBm to -60dBm.
When I got within 3MHz it started to show -50dBm.