There must be a heck of a lot of work around where you are. I tend to agree with you, a good estimator should be able to give you a ballpark number pretty fast, as long as he knows what your specs are. Pretty weird. I don't understand why they want the house finished first, don't they have rough in work to do? I would not settle for registers in the floor either, but that seems like the way they do them nowadays.
Nothing wrong with floor registers.
No Warranty Means- If it breaks in half you get to keep both halves.