Hello Markm4, welcome to the forum.
A stoker stove I would say is very safe. I can't imagine how it could cause a house fire. For that matter, any coal appliance that is of the designs that are currently available, are very safe.
Wood stoves have a deserved reputation of creating creostote fires in the chimney. Coal doesn't leave any burnable residue behind.
The only possible dangers from burning coal would be overfireing, which could create too hot of a stove, or a poor chimney draft and the fumes from the coal getting in the house.
A good Masonry chimney will last just about forever, and cannot melt or corrode. The other power venting devices require monthly maintenance and if negleted can clog up with fly ash.
A properly installed coal burning device, either hand fed or stoker fed into a good chimney, will safely provide a lot of suplemental heat at a very reasonable price.
Hope this helps answer your questions.