If you put Harvin back on kicks, they may not even kick to him either. Minnesota kicked the ball out of bounds as opposed to giving it to Harvin. Plus most kicks are downable anyways but just having him back there could be intimidating. The problem is that I think Harvin would return it even if it was 8 yds deep.
I think early in the game they'll go with Baldwin and if it's close late, they may go with Harvin.
A lot of teams don't put their big $ #1 receiver back on kicks and it's for good reason. It tires you out and opens you up to injury. There's also a reason the league pushed the kick up, it's because it's inherently dangerous to return kicks when you have people running full speed at each other.
I'd rather keep him on the field in our offense than risk injury in a kick return or two. He changes our offense completely and changes their defense completely. He'll draw double teams or coverage rolls to his side which will help our struggling pass offense and then you'll have Tate, Baldwin or Miller/Willson with better looks.