I've always used chase cam and it's a habit I haven't been able to break. I've only tried to break it a few times, but that didn't last long. I don't really see any downsides to it except for less immersion compared to cockpit...which everyone agrees sucks for close, clean racing. I can see all around my car, even immediately behind it. I still use radar, but it wouldn't even be necessary if chase cam had a rear view mirror option.
Bottom line, use whatever view keeps you the fastest and cleanest. The physics remains the same for any view, it's just that you will naturally react differently because of how you perceive your relative location. As a result of this, I often release steering lock too late and have needed to train myself not to do so. Any time I try to use bumper or roof cam, I tend to turn in too late. But those are just things I would need to adjust to.
Don't let anyone tell you you can't be fast in a certain view. For at least the 3rd time now, I saw a World Tour participant using chase cam. The latest was TRL_TSUTSU, and he is literally one of the fastest guys in the game right now. Go ahead, tell him chase cam is inferior!