Big Hitter Silver Rough is lower powered, stiffer, and more control orientated. I prefer the 17.
Big Hitter Blue Rough is springier, more elastic and livelier. No other string like it IMO in terms of being able to generate action and unpredictable movement on the ball off the bounce. I prefer the 16. 17 just seems a bit too lively for anything other than a lower powered racquet. That said, I like adding Silverstring 1.20mm as a cross to BHBR17 mains. Just stiffens the stringbed and adds control whilst allowing for the BHBR to provide spin and action on the ball.