Equinox or Mansfield in Double sided enclosure? Pics attached

Hi Friends,
I am having some serious anxiety about my decision. Many folks on here say I will not regret going bigger, but my local dealer (the sale card crumpler ) tells me the Mansfield is a better choice because it is better to run the stove at capacity, rather than run a bigger stove with a smaller fire due to creosote accumulation. Not sure you agree. I was all set on the EQ before he pretty much talked me out of it. The $1,000+ I would be saving with the smaller stove and smaller chimney made it easy to listen to his argument. He said he would only put the EQ in an auditorium size room. I have a feeling after seeing these pics, you all will have a few other opinions. The house is 3400 ft total, 1800 first floor, 1550 second floor. Fairly drafty, 9 ft ceilings first floor, vaulted ceilings in the first floor "sun room" and all 3 bedrooms upstairs. Right now, we only use the furnace on the first floor and heat gets upstairs pretty good to heat the BRs. There are several return ducts close to where the stove will sit for air circulation via furnace fan.

My goal is to put the stove inside of the double sided masonry structure 44w x 50d x 38h. Class A chimney will be run straight up through second floor BR, then attic, then out.

I do not know how to post a pic and type a description under it yet, so hopefully these pics give an idea. The wall with the bank of windows is opposite the fireplace. The "preview" doesn't show the pics. If not, I'll try again.
Thanks for your input, much appreciated. If I can return the favor with advice on my areas of expertise, please let me know, I run a Deck Maintenance business and also PT Realtor.

The guys at Woodheatstoves.com have been helpful and respond fast, even answered an email at 10:30 at night. Impressive. Anyway, the total chimney height will be about 30 ft., straight up with at most a set of 30 degree bends toward the top. If I ran it straight up and out the roof from where the stove will sit, it ends up coming out thru the roof about a foot outside the existing chase. I'd like to bend it thru the wall of the BR above the stove into the chase to save myself some work on expanding the chase. The existing chimney was B vent for a gas log set that used to sit in the fireplace, run thru the boxed in area above the brick, but the Class A won't fit safely.

The Chimney area that Dave is talking about is actually the original 1920's fireplace and chimney that was knocked down to only about 7 ft, just below where they built the second floor over it when they rebuilt this house in 1994. On either side of that 7 ft of original chimney, they built the brick and granite facades in 1994, while leaving the original 1920's structure intact. So yeah, it IS a shame to put soapstone into all that masonry, but I'm not the boss, I'm married.

Theses pics are looking into the hole I cut out above the brick facade, looking at the top of the old chimney in there. Also a few pics looking up thru the chimney at the subfloor above where my Class A will run, and one looking down into the old chimney from above. This install has not been an easy process, and I haven't even started! I can guarantee I have more hours logged onto this site in the last month than most

Thanks for your input friends.

I was forced to go with the Mansfield due to chimney clearance issues. I'm going up thru a 2nd floor bedroom, then diagonally thru an exterior wall into an existing chase on the outside of the house for the last 12 feet of a 30 foot run. What a cluster #@$%. I could have crammed the 8" chimney in there with bare minimum clearances, but wanted some extra clearance going thru my son's room. I'll sleep better at night in exchange for an occasional blast from the furnace to supplement. In my case, I don't plan on losing much heat from my setup because all that masonry is contained in a 8x8x8 foot area in the center of the house, which I'm hoping will act as a giant Tuklivi and actually help me once it's all heated up. I will be burning 24/7/180? once I get rolling. I work from home during the winter and feeding the Mansfield regularly will not be an issue. Finally ordered the Mansfield yesterday from Woodheatstoves.com. I'm a little nervous buying from someone across the country, but to be honest, I've paid two different local companies to come out and look at my situation and neither of them gave me the impression that they would pay as close attention to the details as I will. One advised to install in the fireplace with no mention of determining EXACTLY where combustibles were located around the masonry, and the other had to check on clearances for Class A pipe! Thanks to the gang on this forum, this is the most fun I've had in a long time (and I race Motocross for a hobby!) I will be creating a thread of my install when the stove arrives in 7 - 10 days. Good luck with your project.