bigsteve, HDEO = Heavy Duty Engine Oil. You were very close.
Yes, I suppose using a non-detergent oil may allow bits of shavings, solid byproducts, etc ... to drop out of suspension and accumulate at the bottom of the pan ... but these contaminants won't be a problem if you change the oil regularly, especially when the motor is very new. Personally, I don't want that junk accumulating in any engine of mine ... I want it OUT.
Very few engines call for non-detergent oil these days. I feel the ones that do are doing so for the many dimbulbs out there that would never think of changing oil in something small like a mower. For this lazy, short-sighted approach, non-detergent oil may keep the engine alive a bit longer ... maybe. But these neglected engines will have their lifespans shortened for sure.
In really older engines (some from the 50s and earlier) with poured-lead bearings, detergent oil may actually slowly dissolve the soft bearing material.
Otherwise, leave the non-detergent oils on the shelf.