I'm glad that you're pursuing making your Lopi Freedom operate better. I don't know that particular stove, but we had a smaller Lopi Revere, and it had better burn times than you are describing. It did have a square firebox, however, and that could account for the difference. A large firebox isn't great if you can't use it.
I've never run a Blaze King, but several years ago we actually planned on replacing our Lopi with a Princess Insert. Our heating goals had changed, and the larger firebox would have been nice. We ended up moving, and so I can't give you any real world data on that because the change never happened. (We had bought a reduced price insert but ended up selling it without ever installing it.)
We moved to Texas and pretty quickly decided that we wanted wood heat down here, too, (we hadn't been sure at first that we'd need it given the climate). We thought a lot about Blaze King because we thought this was an ideal climate for "low and slow." If we had opted for a freestanding stove, we would probably have gone with a Sirocco, but an insert ended up being best for our needs, and no Blaze King inserts would fit. Not a lot of inserts would fit quite frankly, except some really small ones, and we decided we weren't going to spend the money on something that wouldn't meet our goals. Thankfully we found an Enviro insert for a great price, and it's 2.5 ft firebox gives us room to load our twisty live oak when we want to without undue Tetris playing.
Our biggest worry with having a tube stove was whether we would overheat the stove area, but we've discovered that it very rarely happens. (We did have a recent experience where we got the stove room to 80, but the funny thing was that no one minded.) We do load less wood or let it go out with a sunny, warm afternoon, but we think one of the biggest factors in our not overheating is the sheer volume of our home. It's large, though the heat from the insert doesn't reach all of it, and it has a lot of high ceilings. The square footage doesn't tell the whole story. The cubic footage really matters.
All of that is to say that I understand your concerns with the Lopi and your desire to repeat your experience with a Blaze King. I do wonder, however, how much that cathedral ceiling in your great room is affecting your experience of what the Lopi can do and whether it would eat up so much heat that you'd need to run a Princess a lot harder than the "low and slow" at which they excel. Do you have an infrared thermometer to measure temperatures up there when the stove is running? Do you have a ceiling fan or two to help push the heat back down?