I;ve always thought limit was 400', I guess that's a USA limit, but, your right, Canada rules state 300'. I do try & stay to limits, even though I;m out in the sticks. You get those home builts, & Military heli;s too, that fly very close to the 400' limits. With home builts, you get a warning they are coming as they are loud & slow, but, the helio's, seem to come out of nowhere & are on you in seconds!
I had a military helicopter fly over me on Sunday, man he looked to be at my height, but, I guess its the scale of them as he passed by he was 100's of feet above my P3A.