Dr. Colin Gibson
Growing A Healthy Child, Secrets From A Wise Old Doc
has a chapter on orthodontics that would answer your questions. Do yourself a favor and order a copy.
Metal braces or clear braces both work at the same rate and same efficiency. You will get a fabulous result whether you choose to have metal braces or clear braces.
Metal braces are the gold standard of orthodontics. They have been around for a long time. One of the things we learned about moving teeth is it is the amount of force on the teeth that is the most important factor and it is not a heavy force, but a light force we are looking for. When more force is added the teeth do not move as smooth as we want them too which makes the accuracy worse. So, as long as you achieve the optimal force for the most parts metal braces work just as long as anything else. One other thing to consider is moving back teeth. If you are only interested in your front teeth looking nice and your back teeth are fine, then moving just your front teeth will take less time and be less costly as well.
Hope this helps.
My best to you!
William F. Scott IV, DMD