Signature Suites on Reflection are not a new category. It was originally on Reflection when she debut. Along with the Reflection Suite, it was going to be a new category added to the other "S" class ships. But, because of Covid, the "revolution" was delayed/cancelled.
The Signature Suites and Reflection Suite has their own private hall way. Only passengers in the Reflection and/or Signature Suites's room key works on the door to the hallway.
The rooms are well insulated from surrounding noises. We never heard anything that was disturbing. I believe you would love the Signature Suite. π