The parting was amicable; I've finished off my "start-up project", so it's time to find something new. And, I'll still be working in service of the first project as need be. But, everyone seems to believe me when I say that (a) there are others on the project (now) who are more skilled at its innerworkings than I, and that (b) although I could learn those innerworkings as well, that would not be the best use of my own skills. The trickiest bit in all of this, though, was me being able to say I wasn't best suited for my current project, and that some other project (in particular) would be a better match for me. The company relies largely on luck in placing new engineers (esp. Ph.D. engineers) in projects.
So, anyway, I'm working on something else now. And, at present, I can honestly say I'm really excited about it. 8) It's a lot more up my alley, related to my Ph.D. work, and there's more, obvious things to sink my teeth into. I can also see that the project will have a definite conclusion; either we'll succeed or failure, but we'll know within several weeks, and can regroup at that point. Much better than the possibility of devoting several months more to a project and not having anything to show for it.
So, in the end, I'm more upbeat about work now. I can wrap my head around what I'm doing; I can share more of the details of the project with others (I can at least say what I'm working on); and I feel that I am particularly well-skilled for this position, that I'm bringing to bear more than just an undergrad education of coding. And, perhaps most importantly, I can look forward to going to work each day and enjoying spending the entire day hammering away at the task at hand.