I have had fix a flat work just fine on a couple of occasions. A helpful tip I've learned is that I seem to get much better and faster results when I get the weight off the wheel/tire being filled. I personally buy the biggest can they make and would not recommend the can the comes without the hose.

I haven't seen a detailed explanation and can only speculate as to why but Fix a Flat does not recommend their product for Z rated tires or motorcycles. I suspect it would still work but you might be ruining the tire in the process.

Having said all that, I still would not go without a spare.

I'll also second or third the recommendation on work gloves of some sort. I use mine frequently.