I bought a Genesis 5 heavy duty about a year and a half ago. Mainly because I like the idea of "heavy duty", and that was what the implement dealer had ready to go. However, when they say heavy duty, they REALLY mean it. This thing is a beast! My old JD 4700 could not maneuver it without picking up a front end loader bucket of dirt for ballast. My new 4066R can barely maneuver it without the bucket load of dirt, but will pop wheelies when going up hill. I plan to get some sort of front weight kit for the 4066R, just to make maneuvering the G5HD more comfortable while still having access to use the front bucket.
Both tractors will not lift the G5HD with the tractor at idle. The throttle needs to be at a higher setting to get enough oomph to pick up the 3 point hitch. Again, really really heavy. If I had it to do over, I would NOT get the heavy duty model.
To emphasize just how heavy and well built, while loading the just arrived unit onto a trailer for transport to the farm, the pallet broke allowing the unit to topple off of the fork lift and land on it's head. And it did not just roll off, it fell from a height of 3' or so. I was just sick to my stomach, thinking I ruined my expensive new machine before ever putting it on the tractor. Once up-righted and inspected, it had a broken plastic knob on the transmission, a slight wrinkle in the grain box, and two of the plastic windows were popped out of place. RTP was kind enough to send me a new plastic knob at no cost, the plastic windows were siliconed back into place, and I decided to live with the slight wrinkle in the grain box. I truly believe any other machine would have been crumpled, possibly beyond repair.