I would prefer to go with 3 RB + 1 FB and kick that extra roster spot to OL/WR/TE because those guys will see more use. Not saying we'll do that, but we're not really going to use 4 RB's, and none of the guys we PS/Cut is likely to be picked up anywhere else. As fans we tend to over-rate our own players, and RB's are easy to find. If they can pass protect, they're never available, so finding a RB who just wants to run is easy peasy.
Personally, I think we'll go with 4 TE's, because we'll use 2 TE offenses a lot, and we need 2 inline TE's, which means Smythe + ??? so that's where I saw Dwayne Allen fitting. Walford has shown well, but I think he'll be the odd man out.