Yup, I couldn't resist the urge either. Complete waste of powder. Complete waste of money on a sorry rubber buttpad from Walmart and the duct tape I had to use to make it stay on. Complete waste of leather for the more attractive replacement buttpad I had to make to restore the rifle's dignitiy. Complete waste of mounting bolts that my steel plates hung from (they bent and failed). Complete waste of "man cards" (a few of my friends turned them in after shooting these loads without a buttpad).
But I don't consider it a complete waste of time. I thoroughly enjoyed the experience, learned a lot, and was impressed with what the 45-70 can be pushed to in a Miroku/Browning 1886. I'll probably always have a few of these heavy loads in stock "just 'cause". But I'll wholeheartedly agree that loads that hot aren't necessary to get the job done. Their biggest practical advantage would be in extending the EFFECTIVE maximum range, and the limited practical range with iron sights pretty much makes that a moot advantage anyway. Still, it is a hoot.
I made this video 4 years ago, very soon after I got the rifle. You'll probably want to skip past the intro, unless you like being bored.