Interesting question. I can't say that I know the answer, but I'm posting because this subject is also of interest to me. I am currently running a full function preamp with a separate amp, but I am considering moving to an integrated amp with a separate phono stage.
As with anything in audio, I highly doubt that you will find a clear winner in this debate though.
As with anything in audio, I highly doubt that you will find a clear winner in this debate though.