I definitely agree with this. Jim liked to endlessly tweak his models. I share some of that propensity. It’s kind of the 90% solution - You spend 10% of your time getting to the 90% solution and the remaining 90% of your time solving the last 10% of the problem. I think you have the 90% solution, regardless of the specific BV dataset you use. Likely the next obvious tweak would be to improve the BV estimates. As you say, that involves a lot of time. Jim offered a post on how to do that is this thread: OT bond funds - Mechanical Investing - Motley Fool Community. I think @DTBoojum also made BV estimates that he posted to these boards, and he’s still active. Perhaps he’d be willing to share? It would be interesting to see how the models might differ using different BV series. Probably not a lot, indicating the model has some robustness.
Anyway, I’m not throwing work on anyone’s plate 
I really appreciate the work that has been shared here. I’ve been wanting to go through the same exercise but never got around to it.