I've changed the wheel at the roadside twice in all my MOG years. I wouldn't go anywhere without a spare. I had a puncture in my MGBGT V8 years ago and used the goo. Utterley hopeless. And it ruined the tyre; no-one would repair it as they couldn't guarantee removing all the useless goo. In the end I made such a fuss to the goo manufacturer that they paid for a new tyre for me.
My little Abarth came with goo and no spare so I bought a spare and it's in the boot..in the space where the spare used to be fitted!
Re spacesavers.....many (MANY) years ago I was in a Porsche 928 and we had a puncture. On went the spacesaver, no probs. What to do with the enormous punctured wheel though? No way would it fit in the car. In the end we hid it in a hedge nearby and went back for it later in a Volvo estate. Different days....
Nick