I've never used a pulling sleeve. I had a job where I looked at using some, but after finding out the cost, I went a different route. Crouse Hinds calls them "pull boxes" and says they are listed under UL standard 886. They are also listed for use in classified areas and can be used as splice points.
I would say that if you install a C fitting as a required pull point, then the C fitting must have an opening large enough to allow the conductors to be pulled out at the fitting(see 370-28). If you install it as just a soap point and you have other boxes or fittings for the required pull points I see no problem.