I don't think Warner is worth having at all. He's obviously still injured and there's no reason to believe that he can regain last year's form. I'd drop him and hope that some idiot picks him up and plays him against you, only to have him replaced after a few series.
I'd certainly hold onto Bulger, who is the highest rated active QB. We could see him start at least another week, when the Rams start working Warner hard in practice and see that he can't go. Even if Warner starts, I'd say it looks good to see Bulger again.
Warner will do what Eason did in his last season with the Patriots ... come back from injury and poor play and lose a crucial game that the real starter could have won.
If Pennington is available, I'd drop Warner in a heartbeat, but with Bledsoe on your roster you don't exactly have to panic
If you drop anyone, drop Warner. We haven't seen the last of Bulger.