I like Dobbins a lot more than Henderson, and feel he's one of the biggest values in the "dead zone" (and I'm already sick of that term).
That said, Dobbins coaches have been maddening in their usage. He's clearly the best back on the team, but they'll likely insist on getting JAG Gus, and maybe Justice Hill or Ty'Son Williams involved. It won't make sense, but it's what they do.
But if they don't - and if Dobbins can get something like Mark Ingram's rushing workload (~200+ carries) + 30+ receptions he should be a fine low-end RB1/RB2 with upside.
To me that's the only question mark for Dobbins.
With Henderson, I have concerns about durability & talent. Right now opportunity is his strongest attribute, and I can't shake the feeling that the Rams are going to bring in a veteran. The worst case scenario for Henderson owners is the Rams going all the way through preseason seeing what they have in the unheralded backups, then everyone drafts, then they bring in a veteran back to share the load/use in short yardage. I have him as more of a pop for sure, but these are indeed two players that could go either way.
If I'm at the 11-12 turn & Dobbins slides to the end of the 3rd round, I'd have a very difficult time not taking him there. By the time I draft at the end of the month, I'm guessing Henderson is (at least) a 5th round pick, and maybe he climbs to the 4th.