If you want a long burn time, don't get the lopi freedom. I have to get up in the night and add two logs or it will be out in the morning with the fan off. I get a four hour burntime of decent heat. Quess I haven't figured something out. Do know because of the low secondary tubes you can't get more than two good size splits in at one time.
My limited experience with the Lopi last spring was that I had no problem loading it up at 11pm, turning air down low and waking up at 7am to a warm house and it just needed some small splits and a cracked door to get it going again. That's all I need it to do. That was with 5-year seasoned oak, which unfortunately is all gone now.
TE