While I understood what was going on in my head, looking at my post a day later, it might have seemed like a dismissal. It was not. I very much appreciate you valuing my hide as well as the wisdom of your beloved. Pull the trigger and go would NOT be the approach I would take. A professional hand trencher works the same way as a chainsaw although its blade is a bit different. The rotation direction is the same and in fact there is one manufacturer who offers a trenching kit for their chainsaw. The kick on the chainsaw and the risk of the chain flying wouldn't be much any different than with wood: too aggressive of a bite could lead to trouble either way. Naturally any large rocks would have to be hand dug. (Large is defined by the chainsaw/trencher) I don't think any trencher is designed to cut through rock, but up to a certain size, it can just knock them out of the way. I would guess in my soil if it isn't frozen that would be about a 1-1/2" diameter rock tops - anything bigger would probably have to be dug out (I have a pick/mattock that can move the world). Since I don't actually have a whole lot of use for a full scale chain saw, I am looking at a $40 electric with a 14" bar so I am sure it will stall before things get too crazy and if after 15 seconds it seems like the "stupid" is turned up too high, I will abort. I will also be using steel toe shoes, knee pads and a full face shield.