I'd be careful about calling it mid-"grade". Octane and grade are often confused, and from my research, the only reason for upping the octane is for engines that require it. Most engines are optimized for 87 octane fuel, including the Rogue's so I would suggest it.
Gas companies do a really good job of trying to upsell gasoline by naming it the "premium" grade, and introducing cool sounding chemicals like CLEANTRON and MEGASPEEDATHOL to entice you to spend that extra penny, but I'm finding that this might actually dampen the performance you get from your engine, and possibly even damage it in the long run.
I'm no expert though, but take a look at wikipedia's article on Octane ratings: . http://en.wikipedia.org/wiki/Octane_rating