I bought a 17-4 for a very reasonable price due to a broken hammer spur years ago. Bobbed the remaining spur plumb off and have run it in DA only ever since without any dramas. I have plenty of other K frame .22s, so it hasn't been a limitation.
For Speed Challenge, that spur might as well not be there.
But amassing some spare parts isn't a bad idea.
Which reminds me of of a tag line from one of the regulars on Brian Enos' forums: (Probably paraphrasing here) "Hammer spurs are for midnight cowboys." (Fellow called "carmoney", IIRC.) Not altogether sure what that means, but those run and gun types don't have time for super precision, they just need rounds on target straight away.