A fire burning in an unattended shop is cause for concern. Just keep the area clean and make sure of no quick flammables in the immediate vicinity, and have the stove up on some surface that won't ignite from some ash that might fall out. A stove that has good controls where you can shut it down when you leave, or just have a slight fire left burning, I think is good. No problems myself after many years. I'm more concerned about sparks after grinding on something, maybe going into some wood dust and causing something after I leave. I'm real careful about that, and generally keep a well swept up shop. I monitor the flame so it still isn't blasting away when I leave for the night, that is pretty much stop chucking in wood awhile before I know I'll be going home. Sometimes i might be heading home and think to myself, did I close the air intake? I'll go back, but I always have. Just ALWAYS be careful and you are ok. A wood stove in a shop is great. My stove has a damper in the pipe, you don't see those so much anymore. I like it for even more refined monitoring, and the pipe above quickly cools after closing it.