I think the two areas that you might benefit from upgrading are the phono stage and the power conditioner. Manley just came out with the Chinook phono stage at $2kish and it is based on the Manley Steelhead circuitry. Seems like you have a predilection for Manley so hopefully you have a local dealer who can lend you the Chinook to audition in your system. From what I have read, the Furman conditioners have had mixed reviews. You may want to check out other options from Shunyata or Audience or Synergistic Research as a potential upgrade path.
However, I agree with Onhwy61's initial reaction which is if it ain't broke, don't fix it. If you are satisfied with what you are hearing, then put the "upgraditis" aside and just enjoy the show.
Good luck.