No one at the border is going to care about a Radar detector in your saddle bags. And I've never heard of a US person coming into Canada getting searched unless they are suspected of bringing in drugs.
Paging Charlie Hoss, Polarize and sullivan to the white courtesy phone, please

As for while your in Canada. I've never heard of anyone getting searched on the side of the road or loosing a radar detector. Cops are far more easy going here than in the US. No one is going to pull a gun on you like they did me last year for a simple driving infraction. If while your here your going to be taking a more spirited ride, you could always leave it in the hotel, but I wouldn't be concerned.
Hey maddad! you a poh-leece man or sumthin' ? I'm sure there are lots of people getting searched and having stuff confiscated that
I never hear of

As far as LEOs being more easy going here than in the US, thankfully, I can't speak to that. Well....except for crossing the border last month when I mentioned 'Fairlaner' and 'beemerdons' and I was 'detained' for about half an hour
Er....um... WE take
spirited rides all the time (

) and we don't use no steenking radar detector. And riding to Cape Breton, you can't leave your RD in your motel room.
Leave the RD at home, Freddy ! Just sayin'