Interesting.
Growing up in Farm Country there was always Equipment of some sort and lots of Young'ens on Mini and Dirt Bikes running around through the fields and on the roads through the woods. We didn't have ATV's back then, as the 3-wheelers were just coming into existence.
Anyway, I always felt the Deer on those properties got used to the sound and didn't associate it with Danger. I remember several times where I used a vehicle or some sort of equipment to get to a hunting spot with no bad effect.
Now Today, that might no be the same. Pretty much gone are the small Family Farms that were all over back in those days. Still if the equipment you use is the same as you use during the Hunting Season I would think the same effects would happen. I can say that I used my ATV to disc up ground on my new Lease set posts with Cameras on see what was using or crossing there. It didn't take long for the deer to show up on the cams after I did the work.
Personally I think it comes down the Association. If they learn to associate the sound with DANGER, that is the reaction you will get. If they learn to associate the sound with FOOD or NO DANGER then I think that the reaction you will get will be different.
Just for Thought, look at Spin Feeders. Some claim their Deer run fro them when they go off, yet others report the deer learn that the sound means FOOD and they actually come almost running to it.