I know 4 people that have or have had Mahoning stoves. I talked to all of them when I was considering purchasing a new boiler, I will paraphrase our conversations below.
Person #1 - Just installed a new unit this year, its his first OWB, he absolutely loves it, he heats about 3,000 sq ft. house and 30'x40' garage. He burns coal and wood.
Person #2 - Has 10+ yr. old Mahoning. He also loves it. He heats 2,000 sq. ft. house, large garage, DHW and Swimming Pool. He burns it year round and claims to only burn 8-10 cord per year. He doesn't burn any coal.
Person #3 - Has 10+ year old Mahoning. He complains about its efficiency. He doesn't keep track of how much wood he burns but says it is "A LOT". He readily admits that his underground lines are poorly insulated. He has a bare strip of ground from stove to house all winter.
Person #4 - Owned a Mahoning in the past. He does nothing but bad mouth it because of its poor efficiency, and then praises Central Boilers. (Full disclosure: He was a CB dealer for several years)
I live in Western MD and there are a lot of Mahoning stoves around me also. That's everything I know about Mahoning, for what its worth.