The SD footage in Power Play is OK. Not quite blink-and-you-miss-it, but it's not very obtrusive.
I credit the nature of that scene more than anything. It's in a pretty dark area (Ten Forward) and doesn't have many close-ups. The other SD footage this season, of Wesley in the well lit ready room in The First Duty, is a bit more obvious.
But in general I do think CBS-D did a bit better job handling the SD upconversion and color correction this time around.
I think this season's SD footage is handled better than the SD footage from BOBW II in S4.
I think it's also due to the fact that by Season 5 the show had switched from the 1" NTSC composite tape used for Seasons 1-3 to, from what I can tell in the 25th anniversary special (where a ship shot from Redemption is up), the component video Betacam SP (it couldn't have been Digital Betacam, as that system wasn't out til 93 and the decks in the special didn't look anything like any D1 decks I've seen) was in use.
Otherwise, I found the wide shots in the SD material are the worst looking, while close-ups were pretty good.