If that's the need, I'd just say to them that the spurs give you another tool to work with if they balk to go on trail.
I would think if you always ride without them and suddenly they realize you don't have them, they might test you. If it were me and I were trying to get over that, I'd be more prone to carry a crop with that horse for awhile, neither is more or less humane, depends on how and when they are used. And I'd be more likely to give a crop to ecurbh than I would spurs. You can't accidently use a crop at a bad moment trying to hang on. ;~D
Good point. But:)...that is why I use them all the time. I think your point would mostly be a problem for the occasionaly user of spurs.
I was told by a trainer, that it is best if you use spurs to put them on and leave them even if not riding. You "subconsiously" learn to always remember they are there and compensate.
Becky