Is an integrated better or an improvement over separates? Unequivocally no. However, the more important factor that may be missed in this query is: Have you found a synergistic combination with an integrated that is very magical and satisfying? That answer is apparently yes. Should you go out and spend a large amount of money trying to improve upon what you currently have with separates (chasing after a small improvement)? Probably not but that is your call.
Are integrated amps technically better than separates?
I'm assuming we are talking same class of amplifier and the integrated has the features you want. I'm thinking the integrated could actually be an improvement over separates due to being a more "direct" connection. Taking away the flexibility factor of separates, is my line of thinking correct?