In my experiences the cops don't treat you any worse. I've been caught by hand-held lasers a couple of times (just doing a few k's over) with the radar detector in full view. I think it actually makes the cops happier, because they managed to "catch" you even though you had a radar detector. The cops either mentioned whether it went off or completely ignored the radar detector. Just given me a warning or a ticket and sent me on my way, didn't start giving me a hard time with a RBT, checking tyres, asking me to pop the hood, etc.
The multinovas are getting phased out anyway and replaced by laser so it doesn't matter if they ban them eventually. Everybody will just end up getting those parking sensors that also just happen to jam laser. I find the radar detectors are great for knowing when emergency services or roadworks are about... I've always wondered how deaf drivers know about emergency vehicles without checking their mirrors for flashing lights every second?