Ingram drafter here. Dynasty is not a place for snap decisions. Ingram has the physical skills and talent to start in the NFL, but just like 99% of other RBs, he'll probably take a year or two to hit his stride depending on team situation. Sproles being there raises some eyebrows, but I still like Ingram's core talent.
To give some perspective, I drafted Ben Tate last year and he went on the IR before he could even play a down. Should I have cut bait? Of course not, he's looked real good when he's seen the field and given that RBs have careers of usually 2-3 years, I'm content to wait on him too. Think about how long Michael Turner owners had to wait, but they were paid handsomely if they had the stones to hold on for the ride.
Quick decisions in dynasty can lead to looooong periods of regret (case in point, my dropping Hillis like one week before he went off and snatched up that starter title). Hold on to Ingram.