I am not a dozer guy. They will have to weigh in their thoughts.
You want to do it yourself, and that gets tricky. You mention that you don't want to berm the edges of the pond and that you have places to put it. With those parameters, it sounds like you need a trackhoe and dump truck. You don't want to pick that dirt up any more times than you have to with the bucket. Get it in the truck the first time and go.
Now with a dozer, you can push it out and away, but how far away do you plan to go? And do you want to disturb the ground between those two points? I imagine the distance pushed would be a crucial factor on whether a dozer can do that portion of it, or not, better than a dump truck/ track hoe combination. Also, will the ground get to soft even for a dozer? Will the springs be to great to keep ahead of them?
Renting? That can get real expensive fast, especially if you don't know how to operate it the minute you get on. When my dump truck took a need for repair, I looked into renting one. No one around here rented them, some kind of rules against it I guess. That left me with fixing it, and putting everything on hold. Luckily it worked out with the weather. Which is another thing for you to consider. Once you start getting that hole dug, you will want to stay on it, non stop till your done. Nothing more frustrating than working a day or more getting water pumped, etc and then work on it for a day and then quit. Repeat to work on it again in a week or so later. Or a storm comes thru and fills the whole thing up when you only had one more day to go.... ugh.
Whatever you decide on using, considering buying and use it around the place on various jobs first to get used to using it. Then resell when done, or not
. Never know when you want another pond!!!!!
Forgot to add, that you could dig it out fast with a dozer and pile the dirt. Then treat moving that pile as a "many" year project as you need some here/there. However, once you get past about 1/2 acre pond, that dirt pile would become staggering, at least in my opinion.
