I'm in a similar situation: I have the Spectrum Classic heating 1500SqFt of poorly insulated house. During very cold snaps it just can't quite keep up. During those times I find one of my many hooded sweatshirts and put it on rather than turning on the electric baseboard heaters. The house I grew up in was large and old and no woodstove on the market would heat it sufficiently when the temps dipped so I've never had the "This wood stove must work perfectly under all conditions and circumstances" mindset.
Point is, this winter has been an exceptionally cold one for you. If your back up heat has to do some work every 5-10 years I'd say you already have the perfect wood stove. Do you really want to get cooked out every winter just to avoid using propane for an occasional cold snap?
I hear ya, and yes its been colder than usual.But we do get below 20 a lot even with an average winter. This winter has been just a lot more of it. The past couple winters have been mild. My point is, I bought a stove that is rated for 1200 - 2000 sq ft. I'm at 1300 sq ft. With those ratings I should have no problems heating my house when its 20 outside. Its not so much the propane being used as it is the frustration of getting up at 4:00 or 5:00 to deal with the stove. My furnace is in a closet 6 feet from my bed so it wakes me up when it kicks on. Sometimes I cant go back to sleep once it kicks on because I'm thinking " that shouldnt be kicking on this soon".
Yes, I could just let the heat kick on until I'm ready to get up, which is what I do sometimes. But I got this stove because it was rated as high as 2000 sq ft..I also get that all 1300 sq ft houses are not created equal. I've read on here many times " You can always build a smaller fire in a bigger stove"..