I have Damon Clear uppers and Damon metal lowers. Had a hidden right incisor, was fitted with spring/button/elastic to bring that forward. I did not have to use spacers, no further extractions (all 4 wisdom teeth removed many years ago), nor did I have jaw surgery. The underbite "self-corrected" after a few months.
Initial estimate was 22 to 24 months. Currently my orthodontist says I'll be done by summer, which will be about 6 months ahead of schedule. Hopefully all goes well.
See detailed progress pictures and updates in my blog, linked below.
Good luck to all!
