If we are capable of getting to 5CP before the buff expire this would result in extreme bleed ticks. With Rip and Rake already constituting 30% and 20% of our DPS, they would now be responsible of 42% and 28% of our DPS respectively. This is assuming they would be affected by the buff each time they were refreshed. That would yield a 10% increase to our DPS. In other words not something we would ever get from a set bonus, but I like the idea.
Your 4 piece set bonus is quite interesting, too. Auto-attacks would now be responsible for a larger portion of our DPS again (seeing we consider Fury Swipes as a part of our auto-attacks, which is something I do, at least), although not as much as it was back in WotLK.