Personally I am on MK Professional Freestyles ( the MK equivalent to the Cor. Aces), and working on my Doubles with no major problems due to my blades. I did get new skates and did choose to stay with these blades because my coach believes that they are good up to the Double Axel.
Honestly, if your coach and your fitter both think it is best to stay on your current blades, you should trust them, not blindly but trust them. Some coaches, mine included, prefer to work with lower level blades to develop prefect technique instead of working with blades that will "help" you but end up increasing the chances that you develop bad habits.