a lot depends on the Pex line length and insulating quality of the install as well as the insulation of the home/shop...also the location of the home ( VA compared to VT) if you are cold...so is your house. Meaning winds and temps make the outside of the house cold which transfers to the inside and you
... my question is why not keep the stove/insert and use it for some 'romance heat' and burn every thing else in the outdoor wood sucker/boiler. ? Also seasoned wood will cut a cord or two from your 10-15 questimate for sure. but if you got a wood sucker...well ya might as well feed it ANY wood ya got...for now.