But then I don't really understand the "can this (smaller) firebox heat my home?" questions. If you did not run it fully open (in fact, you ran it mostly fully choked) you were *nowhere near* the max BTU output of the stove. The focus on this max (which will likely indeed be higher for the PE) is therefore not all that relevant, I think.
The princess (or any BK stove) can be run wide open. I heard someone saying a 30 box (2.9 -> "3" cu ft) can be burned down in 3-5 hrs (or, indeed, for 24+ hrs in shoulder seasons). Folks in AK run them full blast for weeks at a time. (And yes, one can reload a BK in the middle of the day and push it; if it's cold, my evening reload won't last until next evening - instead I get 10-16 hr burn times overnight. Given that I want to reload at 10-ish pm, I often do a partial load during the day. Given that this happens when it's cold, yes, I'm pushing it a bit then - but nowhere near AK folks or the one telling me "3-5 hour burn down (=max BTU per hour output) can be done".)
That said, I'm *not* pushing for a BK; it appears to me you'll likely be happier with the PE begreen advised you to consider as that's what you are used to. And that is what matters most; that you like looking at it, like burning it, and like how it operates.
My point here is that I think there is no need to fret about the max output, to fret about the BTUs, as you didn't need the max output in your current insert either...
If you ran that thing choked down, then a slightly smaller box won't be a big problem. You had reloads in 10 hours (8 pm to 6 am). Maybe that'd become 8 hours in the coldest part of winter for a 2.6 cu ft firebox? (I don't think this is likely; because the 10 hours was "minimum output". ) Regardless, to me that's still a mighty fine sleeping schedule.
edit: I see
brenndatomu posted something similar just 5 secs before me; I was responding to the OP, not to brenndatomu