To test IEP on 055A or 076, it'll be more challenging. And if something wrong, it'll be not just more costly to fix but also means the capability you're temporarily losing is more critical.Not sure if they should test IEP on a cost sensitive or priority platform like the 054B. Maybe on the 055A or the Type 076, but not something I expect to be mass produced. The ships are going to have to retain something that made the 054/054A series a cost effective and reliable platform.
054B will eventually be cheap and reliable just like 054A. And if you have to fix something to make it work, you still have a lot of 054A.