We have been using Teaching Textbooks for Pre-Algebra (6th grader) and Algebra (7th grader). I have looked at many curriculums out there and I don’t think that there is a “perfect” program. You will get pros/cons for everything out there, but in the end you just need to choose what will work best for you student.
I used Singapore elementary math for my oldest who was a year a head in math at the time we started and have been using Right Start math for the rest of the kids. Both of my older kids transitioned easily into the higher levels of TT and have not had any issues. I don’t find that TT skips concepts at all. From what I remember of these subjects, they are progressing well and are still well above grade level for their math skills. I do like the independence of TT so that I can focus on the more teacher intensive maths for my younger two kids. My kids like it because they can just do their math without waiting for me.
I hope that this helps. Also, I do know a number of families that have switched from Saxon and Math U See to TT with great success and happy kids. 