If us fans were concerned about Akers fumbling, Gibson would be even worse. I won't deny his explosiveness and size, and I won't deny that Washington never used him right, but I am very concerned about ball security and consistency. There's a good possibility he doesn't pan out, that he continues having ball security issues, and I doubt he goes for only a sixth this year and a low pick next year, as he, like you said, had over 1000 yards and was a high pick by Washington's regime.
As for Singletary, I definitely see him as a fit as a smaller power back who can easily break tackles. I also think that he has untapped potential as a receiver; Buffalo never really used him as a receiver, but he did it in college. He's also likely less expensive than Pollard, wouldn't require a mid round pick like Gibson, and offers less mileage than Montgomery.
If I'm honest, though, none of them would be my ultimate choice, particularly if we can recoup a third for a Van Jefferson. My choice is Sean Tucker. Track speed, never fumbles, breaks many tackles, has great vision. Only real weakness I see is third down ability, but if he had it, he'd go in the first round. If Felix Anudike-Uzoman, Stromberg, and Schmitt are gone when we pick, I think I'd pivot to Tucker, just because of elite running back potential.
I agree with you that Akers needs competition after what he pulled early in the season. I just prefer that competition should be young and multifaceted.