The voice of experience. Its hard to beat.
But johndeere, would you buy a small backhoe to dig a pool? And how long did it take ?
Like BrianMO said, he doesn't own a backhoe...
If i was him and didn't own a backhoe and wanted to buy one to dig a pool, (then yes)... I would buy one to dig a pool.
On one of the pools that i dug, it was 4ft. on one end and it sloped down to 10ft, and the pool was 10ft. wide...It took me 16 hours to do the whole thing, and that included shaping the sides, and hauling all the dirt out of the hole.
On the other pool, it was 4ft. and sloped to 6ft. and doing everything took about 10 hours.
My pond is 25X25 and 9ft. deep and i had to slope the sides different than the pools....The pool sides were straight down, and my pond sides are sloped from the top of the bank down to the bottom.... I could back my ATV down in my pond.(only if there wasn't any water in it.

).... My backhoe has a reach straight down to 8 1/2-FT.
Its much easier & faster if you make a ramp and get inside of the hole, and you can use your FEL to do
some digging.
The biggest problem with digging a pool or pond is getting rid of all the dirt, and if you don't have it planned out first, then it can take a lot of hours to finish.... On the pools and pond i had a dump trailer sitting on top waiting, and i came out of the hole with a load & dumped it in the trailer.
If a person knows how to use a piece of equipment he could dig a pool or pond with a 'terramite' that had a FEL and backhoe.... But it would just take longer to do.