Not directly related to different eras of uniforms, but in terms of different situations for different styles part of me will be forever irked at Voyager (amongst a myriad of other reasons) that they did not continue the black-on-division = ship assignment, division-on-black = station that Deep Space Nine seemed to go for in the first few seasons.DS9 did manage a subtle effect with uniforms. In season 5, the uniforms were changed to match the more military grey and black style of the movie First Contact. Then they introduced a story line that Bashir had been replaced by a Changeling. They showed him being held captive, wearing the old style uniform (In Purgatory’s Shadow). This gave an indication that the Bashir we’d seen in the previous few episodes was the Changeling all along. In particular, it was the Changeling that recommended Sisko undergo an operation to stop him seeing visions in the episode Rapture.