In early January, my wife and I bought a Harman P43 to add another heat source in our 2200sq ft home. At late February, my stove company allowed me to trade it out for a P68 - and I think they gave me a square deal - so I'm thankful (Spavinaw Stove in Gentry, AR). I thought others might be interested in my experience because few people most likely do this - where they've swapped out the small stove for the big stove in a very short amount of time - keeping the same venting, and of course the same house, in roughly the same season of the year - exactly same location. I've gotten a lot of enjoyment out of this forum - so thanks for all who interact here. Short version: I really enjoyed both stoves - but after owning the P43 for a bit, I'm enjoying having the larger one. My experience with the P43 included some periods where the outside temps were -14 degrees F (though that's not common where we live) as well as general freezing temps. I enjoyed turning off our central HVAC and seeing how effectively the stove would heat our 2 story 100 year old house.
My wife and I are suckers for the classic design of the P series - since it reminds us of a wood stove we had in a previous house, our first. the 2 stoves look nearly identical, they share the same controls, and basic design. List price the P68 is around 25% more expensive than P43- ish.
Aesthetics - I loved how compact the P43 is - but the flame just looks huge in the P68 - the viewing window is taller. I assumed the 2 stoves would be mirror copies of each other - but the burn pot is a different shape (similar) and of course a bit bigger, wider. Whatever the change - the fire seems twice the size aesthetically in all the heat regimes. We like that.
Cleaning - We've had the P68 for 10 days now and its been considerably warmer, but so far there is less ash hanging around. This is probably because I was having to run the P43 wide open a lot to try to move air and make heat. I'm noticing less ash clinging to the heat exchanger at the top when I scrape it on the P68- maybe because the unit is simply taller and less is moving up to the top. Since we are not having to run the P68 as hard, and it is in Room Temp where its cycling around -
Heating - I am noticing that the P68 makes that pleasant radiant heat far easier and quicker than the P43. I can keep the stove in a low mode where it makes less noise and on a lower temperature setting and we feel warmer in the house than with the smaller stove. That is somewhat important to me because this stove is in the living room and we sit next to it a lot. The distribution fan on the P68 is higher by a few inches and seems more aggressive at high settings - though I'm not sure if its really a stronger unit or not. With the P68 we can more quickly arrive at the "wow that's hot - and it getting hot in here" place - whether I'm in stove or room temp. With the P43 is room temp mode/auto - I frequently set the temperature to far higher than what the room actually was - so that the stove would run hard and get more output. With the p68 - it seems like the temperature of the space the stove is in more closely resembles what I actually set it to.
The hopper is larger on the P68 - and that's been a pleasant change. I felt like the P43 hopper was big but the P68 will let you put almost 2 bags in - so less trips out to where we keep our pellets.
A few negatives - the P68 auger / feed motor is louder - a lot louder than the P43 where it was silent. Hope that doesn't indicate a long term problem. The pellet noise seems the same. Otherwise the noise of the unit seems around the same (combustion, distribution blowers).
Essentially I think I'm experiencing what others have posted frequently on this forum - better to have the heating power and only use a fraction of it, than have a smaller stove that you have to run wide open more. The P43 is rated by Harman between 800 -2800 sq. ft - but my house is on the upper end of that. Don't buy one of these where your home is on the top end of the range! I think I would have been happy with the P43 and I was enjoying it - but I'm enjoying the more powerful unit.
Just in case others are interested in the direct comparison! Thanks all.