About 1990 we had some land reforested. The forester showed up with a large tree planter and a very small 4wd ford tractor. Maybe 3000# with attachment at most. We have all sandy soil. My large IH2500b 8000lb 50hp 2wd tractor loader with full cab and loaded R4 tires had lots of trouble in that sand, so I was skeptical. I knew the forester since high school, so I trusted him. He said that in the past, they'd of had to bring in a very large tractor to do our job. With the advent of 4wd in small tractors, it really changed the way they started doing things. The smaller, lighter machine with 4wd gets excellent traction, yet causes significantly less soil compaction and ground damage.
That little 4wd ford easily pulled that tree planter through the soil up and down the steep sand dunes (the steepness of the soil was why we got the trees 75% paid for by the government: erosion control project).
I think engine HP, PTO HP, 4wd, tire selection, air pressure, gearing, ground speed, soil types, etc... have just as much if not more impact as the overall weight of a machine.
My current machine weighs just 1500# with me on it. It will run circles around a conventional tractor of the same weight and even much larger in tasks such as material moving, lawn mowing, brush cutting, snow plowing, etc.... what it won't do is pull stumps, pull a dirt plow, any brute pulling power tasks, because of the way it's geared. It only has one range, as it has hydraulic motors at each of the 4 wheels. If I changed the wheel motors to larger displacement, it would be a pulling machine, at the sacrifice of top speed. My point being, while weight of a machine is important, it's not as important as getting the power to the ground. There are lighter machines that perform better than heavier machines due to the things I listed above: engine HP, PTO HP, 4wd, tire selection, air pressure, gearing, ground speed, soil types, etc...
I agree that you need to first decide on the tasks you want to accomplish. Then you have to decide how much time you want to spend accomplishing those tasks. Then decide what size implements you need to do those tasks in said time. Then find a tractor that has enough features to move those implements in the given time. Then compare that to your budget, slap yourself in the head a few times, and downsize your plans! :laughing:
Tractor weight is important, however, it's not THE most important thing. It's just one part of the equation.