I never found the RS antenna to be any good for VHF and UHF airband. I have since sold it so I can't compare.
I compared the RH77CA and the Watson Airgainer on VHF and UHF airband transmissions. When close to the signal source (i.e. just outside the airbase fence) there was very little difference. The Airgainer just seemed to quiet the signal better.
When monitoring from a distance (25km line of sight) the Airgainer is slightly better. Once again it seems to have more gain in the V/UHF airband and seems to quiet the signal better.