For one thing, it would be more expensive to buy a new headset, stem and possibly handlebar (depending on the clamp diameter of your existing items) in addition to the labor of cutting the steerer. Secondly, is the O.D. of a threaded steerer exactly the same as a threadless, or will you have to torque down excessively on the stem clamp to securely fasten the thing together, and is the I.D. exactly the same so that a star fangled nut seats properly to hold the top cap securely in place. I just think there are too many variables when simply having a qualified machine shop cut and chase the threads on the existing steerer is simpler and will probably cost less. That is JUST MY OPINION. I am allowed to have one, right Sydney???