Still confused on what to get

For about 5 months I have been doing some research on what wood insert to buy and im still so confused and on what to get. My opening is 41wx27hx22d. I currently have a very old wood insert that can put out some serious heat but my burn times sucks, 3-5 hrs max. It all depends on how much wood i load it with, my firebox size is 26wx15hx15d. Im assuming thats a firebox size of 3+ And like I said its lit out a tremendous amount of heat when full just not for very long. The box does not have your tradition single exhaust output, it has multiple exhaust outputs. Actually 5 3inch exhaust, so their is no liner going up the chimney. It is been here for over 20 years I would say. Chimney is very clean and in excellent shape. Just bought the house not too long ago. Ive been burning all winter long and even on the cold ass days my house stayed at 70 degrees when the insert was burning. I leave the thermostat on at 68 because some nights when the insert goes out i don't always wake up to reload wood. Its heating my upstairs which is around 1500 square feet ranch style house.

Ok so I'm so confused on what to buy as i think their is too much room for a company to say well, you dont have this or that Thats why your not getting 10 hr burn times or whatever the jnsert says it should do. Also the dealers I have contacted will not guarantee the burn times either. I assume since companies are so bold to put burn times(without giving details on how they achieved those burn times) on their website then it would very easy to get those burn times(dont have to be a 10 year burner to get it). I am not a cheap person but I am really stubborn when it comes to reading something and it doesn't do what it states it should do. Im also wondering if wood burning is really for me because of all this information that i believe is not to be accurate. I dont have a new stove so i could be wrong about all of this(sorry) and be very happy with a new one. So all of this being said please dont take it the wrong way but every dealer i have called seems to be like "we will come and install it and thats it. No mentioning of burn times and btu output. If I am going to spend thousands of dollars then i expect to have conclusive results when the install is done right?

I am currently looking at a blaze king princess and have been told many different things from many different dealers. One tells me to get a liner thats insulated, the other doesnt. One tells me thats it does burn long but at low setting, the other say you can achieve on high 8 hr burn times. One tells me that it burns long but the heat output is great. Maybe i am just dealing with the wrong dealers and am getting really confused.

At the end of the is it wrong for me to have a guarantee to at least get double the performance and burning time of the outdated stove I have now? I mean whats the point then of spending all this money then.

Sorry, the insert has its own clay liner nothing else shares it. The actual insert stove itself has multiple exhaust outlets on top of the unit where all the new stoves have a single exuast. Ill take a picture make things clearer when the stove temps go down.

Would you say i am overreacting about times and btus? Or am i write to question them?

Well i was on the phone with many different dealers that sold many different fireplaces. I think i am down to either to a blaze king princess or a fireplacex hybrid. Dealers that are selling them did not make me feel very confident on burn times and heat output. You can see in the picture my insert, maybe it cost 300 bucks back in the day brand new. How can I convince myself to spend almost 5 grand on a new insert that will not double my heat and time or at least same heat but gotta double if not triple my burn time at the same heat.

He has the hybrid? The firebox on the fx is 3 instead of 2.5 on the princess. I have no idea i need to see them in person and on full blast to see the heat output on em. Can you ask em how much he paid for the fx?