Does the p and m use less wood than other models? Sometimes yea, just depends on what your comparing it to, the regular p and m line is the same as heatmasters e series, they are a bit more efficient than the basic designed stoves yea
For the most part, all efficiency numbers are bogus and only attainable in lab situations where there burning crib wood and not even burning real firewood, it's all marketing! Just like empyre or central for example with stoves reaching 90% efficiency, stack temps are still over 300, regardless of what u read, they are over 300 and often over 400, me and others have checked this numerous times. So if ur stack temp is 400, and your operating at 90% efficient that would mean your internal temps would need to be 3000 degrees or better, not happening, I know what the advertisements say, my office is filled with them, but I can't say the companies are lying, because in that lab, they can probably tweak things to get such crazy numbers, but to ever expect anything remotely close to that in the real world is crazy
As far as the new p and m design, I like the idea, but as with every other new design, it's going to have unforeseen issues and stuff that will be phased out over time, but I do like the principle of it