Ned, typical 725 builds are around the 27-28lb mark for a sensible thrashable build.
The 853 frames will be lighter than the 725 frames as all the main tubes are thinner walled. That weight difference will only be a matter of ounces though. People know the Prince Albert and its reputation, and if they’re seriously considering it, they won’t base their decision on whether it weighs 5lbs or 5.25lbs.
If someone already has a current model 725 frame and they’re happy with it, my honest advice is stick with that unless the 853 tubing and engraved head tube (and a few less ounces) really float your boat. The 725 Prince Alberts are still a perfectly good frame design and material. Once this limited run of 853 Prince Albert Classics are sold out, Prince Alberts will go back to being made in 725 again anyway.