United came away from the Matchroom Stadium with a 1-0 win - there visit league victory there since 1977 after a stunning 59th minute strike from Nick Blackman gave the Blades all three points and lifted them to third in the League One table.
Slade said: "I think they were the best side we've played this season. You've only got to look at their record to know they're a difficult side to beat. They haven't lost yet. It was always going to be a tight affair. We needed it to be a tight affair and that's what it turned out to be. We've lost by the odd goal. I think we lost to a good side today and arguably deserved to lose the game but we still had the best chance of the game."