Yes, your answer helps a lot. Thanks.
The only other questions I have are:
1. Does the dough comes out any different?
2. Is the dough better in taste, texture or both -- or should I say, is it sufficiently better to justify upgrading to a better (and more expensive) mixer?
The impression I got from your answer is that the spiral hook's only advantage is time -- i.e., the dough tastes and feels the same, but you can make it faster.