Meadowlark,
I remember a big pond, it's been awhile but it was maybe 3 acres. The pond is by Coffeyville Ks. The cat skinner I was helping said it was built in the depression with people, shovels, and wheel barrows.
There are a lot of ponds that were built with horses and slips also.
Compared to that any size dozer looks great and it proves what can be done with even a small dozer and time. On a bigger dig it can be "very slow" like you said. And if anyone tries digging an acre pond with a 450 they may find that is an understatement.
I will use the cat sizes as I am most familiar with them.
The D3 is an awesome little dozer. With time you can do a good size hole. It has great flotation also, good for mud, won't pack dirt easily.
The D5 is also a great tractor. There is more than 1 professional excavator that makes a living with them. An acre hole you'd have to take a lunch, and anything bigger you'll be camping there.
The D8 was, and probably still is the most prolific dirt moving machine for moving dirt.
My favorite right now is my D9G. It has a semi U blade rated at 17 cu. yds.. That's a semi load of dirt a push in perfect conditions. The brand new D9's only have me beat by 15 hp. Flotation is not great. Compaction is easy to get.
The D6 and D7 are good all purpose machines, big compared to the D3 size.
Probably the most important thing is to buy a machine that will stay running.
If a final drive, motor, or transmission goes out on a larger dozer it's a lot of money. It can be as expensive as the purchase of a dozer, but it probably won't increase the value of the machine very much.
The dozer size that suits one guy wouldn't necessarily be right for another.
I have a very large dozer so I can move a lot of dirt when I need to in a short amount of time, to make a living and still have time for family.
