This really doesn't answer your question...but a 45-70 BFR has been on my "list" for nearly a decade now. Last year, I had the financial opportunity to get a hard hitting, big bore revolver and I decided to go with 460 instead. After many discussions with people I know that own BFR's, I also decided to skip that and go with the S&W X-frame. I will say that the newer BFRs have changed a few things to make them less of knuckle-crackers by moving the trigger guard. They also now offer a bisley grip, which I like.
In the end, I do not regret my decision one bit. I've really enjoyed reloading the 460 round and the x-frame is great to shoot.
With that said, I will still have a 45-70 BFR, one day. My next is to get a Henry in 45-70 (as they're not making a 460 lever). Once I get reloading for it under my belt, a BFR will be the next logical step.