Normally a harness makes it easier for a dog to pull (unless it's a no-pull harness or something, duh).....and a halti makes it so they can't pull. So I'm not sure how you can compare them.

If you want her to pull a sled and wear the harness, but you don't like her to pull on regular walks, then I wouldn't use it on regular walks...otherwise you're kind of defeating the purpose.