Joni Mitchell uses the "gear change" effectively too. But she knows exactly what she's doing and is in full control of the sound she makes. It's a bit different when you get a less skillful singer who can't cope with the break in the voice, so the sound simply fades away or becomes wobbly and feeble beyond a certain pitch. It's all about choosing and controlling the sound you make, rather than being taken by surprise at what comes out of your mouth.

I'd also say to the original poster: an octave and a half will go quite a long way if you use all the notes to advantage - in other words, choose the best pitch for each song. Many people seem to run out of their range at the top or the bottom simply because they started too high or too low in the first place. Even if you don't understand keys, all you need is to work out (by trial and error) the best starting note for each song and use a pitch pipe to find that note when you sing it.

It's well worth working to extend your range too, and taking it further than your speaking range, but make things easier for yourself in the meantime by taking a bit of care with the pitch.

Marje